The 'password' for the oauth:// entry is a string of 46 random characters, and is stored in Options when you enter the regular account password in the OAuth browser window. So, if you changed the account password, Remove the oauth:// token plus any imap:// or smtp:// passwords, if present, restart TB, and enter the new account password in the browser window when prompted.

I have done what you suggest, deleted the gmail entry under “passwords”. When I attempted to send an email to myself I was prompted to enter my password, which I did; I checked options/ passwords and the gmail entry had been reinstated exactly as it was originally. The email I sent to myself was received on my phone but not in Thunderbird – there was a message “unable to connect to imap server, you may have exceeded the maximum number etc.”(cannot give the whole message as it quickly disappears before I can copy). I checked and the maximum number is set to 5; there was also a message that it could not be saved. I also have a talktalk email account on Thunderbird – I sent an email to my gmail account from the talktalk one and it displayed again on my phone but not Thunderbird. When I sent from gmail there was a message could not save, To sum up, the gmail account will now send and receive, but not display in either the inbox or the sent box. The hourglass is constantly showing when the gmail account is selected but not with the talktalk account.

What is your anti-virus software?

F-Secure, provided by my ISP. Defender was causing problems after what I believed to be a corrupted update. Thunderbird was OK until I changed my password with another Google product

Try to start Windows in safe mode with networking enabled. - Win10 https://support.microsoft.com/en-us/help/12376/windows-10-start-your-pc-in-safe-mode

Still in Windows safe mode, start Thunderbird in safe mode. - https://support.mozilla.org/kb/safe-mode

Does the problem go away?

No change at all in sfe mode. No new emails nd still the hourglass and rotating circle top left of screen

No different in safe mode. Still hourglass nd rotating circle op left of screen

Can you confirm you did start Windows in safe mode?

Definitely. Screen background was black and words safe mode top right

Please post your Troubleshooting Information. At the top right of the Thunderbird window, click the menu button , then select Help > Troubleshooting Information. Press the "Copy text to clipboard button" and paste the information into your reply.

Prevent Accessibility: 0

   Accessible Handler Used: true
   Accessibility Instantiator:

 Library Versions

     Expected minimum version
     Version in use

     NSPR
     4.21
     4.21

     NSS
     3.44.3
     3.44.3

     NSSSMIME
     3.44.3
     3.44.3

     NSSSSL
     3.44.3
     3.44.3

     NSSUTIL
     3.44.3
     3.44.3

 Sandbox

   Content Process Sandbox Level: 0
   Effective Content Process Sandbox Level: 1

 Internationalisation & Localisation

     Application Settings
     Requested Locales: ["en-GB"]
     Available Locales: ["en-GB","en-US"]
     App Locales: ["en-GB","en-US"]
     Regional Preferences: ["en-GB"]
     Default Locale: "en-GB"

     Operating System
     System Locales: ["en-US"]
     Regional Preferences: ["en-GB"]

This looks like the very last part of the Troubleshooting Information, which isn't really interesting.

Application Basics

   Name: Thunderbird
   Version: 68.5.0
   Build ID: 20200210021033

   Update Channel: release
   User Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.5.0
   OS: Windows_NT 10.0

   Launcher Process: Enabled
   Multiprocess Windows: 0/0
             Disabled
   Remote Processes: 0
   Enterprise Policies: Inactive
   Google Location Service Key: Missing
   Google Safebrowsing Key: Missing
   Mozilla Location Service Key: Missing
   Safe Mode: false

 Mail and News Accounts
   account2:
     INCOMING: account2, , (none) Local Folders, plain, passwordCleartext

   account5:
     INCOMING: account5, , (imap) imap.gmail.com:993, plain, External
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true
     OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, false

   account8:
     INCOMING: account8, , (imap) imap.talktalk.net:143, alwaysSTARTTLS, passwordCleartext
     OUTGOING: , smtp.talktalk.net:587, alwaysSTARTTLS, passwordCleartext, true

 Crash Reports for the Last 3 Days

 Remote Processes

   Type: Count

 Extensions

     Name
     Version
     Enabled
     ID

       Amazon.co.uk
       1.1
       true
       amazon@search.mozilla.org

       Bing
       1.0
       true
       bing@search.mozilla.org

       Chambers (UK)
       1.0
       true
       chambers-en-GB@search.mozilla.org

       DuckDuckGo
       1.0
       true
       ddg@search.mozilla.org

       Google
       1.0
       true
       google@search.mozilla.org

       Twitter
       1.0
       true
       twitter@search.mozilla.org

       Wikipedia (en)
       1.0
       true
       wikipedia@search.mozilla.org

 Security Software

   Type: Name

     Antivirus:
     Antispyware:
     Firewall:

 Graphics

     Features
     Compositing: Basic
     Asynchronous Pan/Zoom: none
     WebGL 1 Driver WSI Info: EGL_VENDOR: Google Inc. (adapter LUID: 0000000000009a33)

EGL_VERSION: 1.4 (ANGLE 2.1.0.8a050090f926) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_EXT_device_query EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_flexible_surface_compatibility EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_explicit_context

     WebGL 1 Driver Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GT 1030 Direct3D11 vs_5_0 ps_5_0)
     WebGL 1 Driver Version: OpenGL ES 2.0 (ANGLE 2.1.0.8a050090f926)
     WebGL 1 Driver Extensions: GL_ANGLE_client_arrays GL_ANGLE_depth_texture GL_ANGLE_explicit_context GL_ANGLE_explicit_context_gles1 GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_memory_size GL_ANGLE_multi_draw GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_color_buffer_float_rgb GL_CHROMIUM_color_buffer_float_rgba GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_sync_query GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_color_buffer_half_float GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_format_BGRA8888 GL_EXT_texture_rg GL_EXT_texture_storage GL_EXT_unpack_subimage GL_KHR_debug GL_KHR_parallel_shader_compile GL_KHR_robust_buffer_access_behavior GL_NV_EGL_stream_consumer_external GL_NV_fence GL_NV_pack_subimage GL_NV_pixel_buffer_object GL_OES_EGL_image GL_OES_EGL_image_external GL_OES_compressed_ETC1_RGB8_texture GL_OES_depth32 GL_OES_element_index_uint GL_OES_get_program_binary GL_OES_mapbuffer GL_OES_packed_depth_stencil GL_OES_rgb8_rgba8 GL_OES_standard_derivatives GL_OES_surfaceless_context GL_OES_texture_border_clamp GL_OES_texture_float GL_OES_texture_float_linear GL_OES_texture_half_float GL_OES_texture_half_float_linear GL_OES_texture_npot GL_OES_vertex_array_object OES_compressed_EAC_R11_signed_texture OES_compressed_EAC_R11_unsigned_texture OES_compressed_EAC_RG11_signed_texture OES_compressed_EAC_RG11_unsigned_texture OES_compressed_ETC2_RGB8_texture OES_compressed_ETC2_RGBA8_texture OES_compressed_ETC2_punchthroughA_RGBA8_texture OES_compressed_ETC2_punchthroughA_sRGB8_alpha_texture OES_compressed_ETC2_sRGB8_alpha8_texture OES_compressed_ETC2_sRGB8_texture
     WebGL 1 Extensions: ANGLE_instanced_arrays EXT_blend_minmax EXT_color_buffer_half_float EXT_disjoint_timer_query EXT_float_blend EXT_frag_depth EXT_shader_texture_lod EXT_sRGB EXT_texture_compression_bptc EXT_texture_filter_anisotropic OES_element_index_uint OES_standard_derivatives OES_texture_float OES_texture_float_linear OES_texture_half_float OES_texture_half_float_linear OES_vertex_array_object WEBGL_color_buffer_float WEBGL_compressed_texture_s3tc WEBGL_compressed_texture_s3tc_srgb WEBGL_debug_renderer_info WEBGL_debug_shaders WEBGL_depth_texture WEBGL_draw_buffers WEBGL_lose_context
     WebGL 2 Driver WSI Info: EGL_VENDOR: Google Inc. (adapter LUID: 0000000000009a33)

EGL_VERSION: 1.4 (ANGLE 2.1.0.8a050090f926) EGL_EXTENSIONS: EGL_EXT_create_context_robustness EGL_ANGLE_d3d_share_handle_client_buffer EGL_ANGLE_d3d_texture_client_buffer EGL_ANGLE_surface_d3d_texture_2d_share_handle EGL_ANGLE_query_surface_pointer EGL_ANGLE_window_fixed_size EGL_ANGLE_keyed_mutex EGL_ANGLE_surface_orientation EGL_ANGLE_direct_composition EGL_NV_post_sub_buffer EGL_KHR_create_context EGL_EXT_device_query EGL_KHR_image EGL_KHR_image_base EGL_KHR_gl_texture_2D_image EGL_KHR_gl_texture_cubemap_image EGL_KHR_gl_renderbuffer_image EGL_KHR_get_all_proc_addresses EGL_KHR_stream EGL_KHR_stream_consumer_gltexture EGL_NV_stream_consumer_gltexture_yuv EGL_ANGLE_flexible_surface_compatibility EGL_ANGLE_stream_producer_d3d_texture EGL_ANGLE_create_context_webgl_compatibility EGL_CHROMIUM_create_context_bind_generates_resource EGL_CHROMIUM_sync_control EGL_EXT_pixel_format_float EGL_KHR_surfaceless_context EGL_ANGLE_display_texture_share_group EGL_ANGLE_create_context_client_arrays EGL_ANGLE_program_cache_control EGL_ANGLE_robust_resource_initialization EGL_ANGLE_create_context_extensions_enabled EGL_ANDROID_blob_cache EGL_ANDROID_recordable EGL_EXTENSIONS(nullptr): EGL_EXT_client_extensions EGL_EXT_platform_base EGL_EXT_platform_device EGL_ANGLE_platform_angle EGL_ANGLE_platform_angle_d3d EGL_ANGLE_device_creation EGL_ANGLE_device_creation_d3d11 EGL_ANGLE_experimental_present_path EGL_KHR_client_get_all_proc_addresses EGL_KHR_debug EGL_ANGLE_explicit_context

     WebGL 2 Driver Renderer: Google Inc. -- ANGLE (NVIDIA GeForce GT 1030 Direct3D11 vs_5_0 ps_5_0)
     WebGL 2 Driver Version: OpenGL ES 3.0 (ANGLE 2.1.0.8a050090f926)
     WebGL 2 Driver Extensions: GL_ANGLE_client_arrays GL_ANGLE_copy_texture_3d GL_ANGLE_depth_texture GL_ANGLE_explicit_context GL_ANGLE_explicit_context_gles1 GL_ANGLE_framebuffer_blit GL_ANGLE_framebuffer_multisample GL_ANGLE_instanced_arrays GL_ANGLE_lossy_etc_decode GL_ANGLE_memory_size GL_ANGLE_multi_draw GL_ANGLE_multiview_multisample GL_ANGLE_pack_reverse_row_order GL_ANGLE_program_cache_control GL_ANGLE_provoking_vertex GL_ANGLE_request_extension GL_ANGLE_robust_client_memory GL_ANGLE_texture_compression_dxt3 GL_ANGLE_texture_compression_dxt5 GL_ANGLE_texture_multisample GL_ANGLE_texture_usage GL_ANGLE_translated_shader_source GL_CHROMIUM_bind_generates_resource GL_CHROMIUM_bind_uniform_location GL_CHROMIUM_color_buffer_float_rgb GL_CHROMIUM_color_buffer_float_rgba GL_CHROMIUM_copy_compressed_texture GL_CHROMIUM_copy_texture GL_CHROMIUM_sync_query GL_EXT_blend_func_extended GL_EXT_blend_minmax GL_EXT_color_buffer_float GL_EXT_color_buffer_half_float GL_EXT_debug_marker GL_EXT_discard_framebuffer GL_EXT_disjoint_timer_query GL_EXT_draw_buffers GL_EXT_float_blend GL_EXT_frag_depth GL_EXT_instanced_arrays GL_EXT_map_buffer_range GL_EXT_occlusion_query_boolean GL_EXT_read_format_bgra GL_EXT_robustness GL_EXT_sRGB GL_EXT_shader_texture_lod GL_EXT_texture_compression_bptc GL_EXT_texture_compression_dxt1 GL_EXT_texture_compression_s3tc_srgb GL_EXT_texture_filter_anisotropic GL_EXT_texture_

account5: INCOMING: account5, , (imap) imap.gmail.com:993, plain, External

This isn't going to work. For this account:

• set 'Connection security' to SSL/TLS, port 993, and
• set 'Authentication method' to OAuth2

OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, true OUTGOING: , smtp.gmail.com:465, SSL, OAuth2, false

Is there another Identity for this account? http://kb.mozillazine.org/Mozilla_Suite_:_FAQs_:_Mail_Aliases

Visitors just about to arrive. Will reply later today

Everything already set up as you suggest except that authorization was not OAuth2 - changed that and it still does not work. I think the only solution now is to uninstall/re-install Thunderbird and add the two accounts. I have copied my address lists, presumably all my emails will be in the inbox rather than various folders, but I can easily transfer as required. Thank you for spending so much time to no avail - it is much appreciated.

Delete the Gmail passwords and oauth:// entries from Tools/Options/Security/Passwords/Saved Passwords, restart TB, and enter the new password in the OAuth2 browser window when prompted.

I think the only solution now is to uninstall/re-install Thunderbird

You'll be wasting your time. The problem appears to be in your Thunderbird profile. Profile files are stored separately from the Thunderbird program files. The program files are static and do not change (except when you upgrade the Thunderbird application version). Because we store profile and program files separately, you can uninstall Thunderbird without losing your messages and settings, and if something goes wrong with a Thunderbird update your information will still be available. It also means that you don't have to reinstall Thunderbird in order to delete your information or troubleshoot a problem.

I have copied my address lists, presumably all my emails will be in the inbox rather than various folders, but I can easily transfer as required.

It's recommended to create full profile backups on a regular basis. https://support.mozilla.org/kb/profiles-where-thunderbird-stores-user-data#w_backing-up-a-profile

Presumably I could delete Thunderbird, then delete the profile, then reinstall Thunderbird, when a new profile would be produced. All my emails appear to be on the gmail server so would presumably be automatically imported, with the same folder descriptions. I have copied the profile help page to a file for future reference.

Everything already set up as you suggest except that authorization was not OAuth2 - changed that and it still does not work.

What exactly isn't working?

Just as before. I can send an email to my gmail address using the gmail account and receive it in MS Mail, but not in Thunderbird, nor is the outgoing email saved in Thunderbird. No emails received in Thunderbird since 27 January - I am now using the inferior MS Mail.