IS THERE ANYONE HERE THAT CAN HELP OR AM I JUST WASTING MY TIME?

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.

Gmail has reconfigured how it deals with 3rd party apps like TB. You will have to generate an “app password” with Gmail to replace your password in Tbird, if you ever change your password on Gmail or if TB needs to be reinstalled or if you go through an update, etc. I have done this many times and it works for me. Here's a webpage that will walk you through it:

https://support.google.com/accounts/answer/185833

Thanks for the replies; however, TB was working great till I change the password in gmail then applied the same password in TB and it would not reset the password in TB. I have done this password change every two months, until this latest update (which now has updated to a higher level.) And this AM, nothing changed; that I knew of...read further.

Could sign out and back in to Gmail but never via TB for this ONE email account. My other gmail addresses were able to sign into Gmail continually. It was just that one.

Found info on line at another location with a suggestion to delete a file (PKCS11) in my profile, then reboot the computer and sign back into TB and then try the new password and it worked; and is still working. Problem has been solved.

Why after years this happened; who knows. Per the website I read about the file I guess it can cause a new password from overriding an old password. And I guess that is what was happening.

NO FURTHER INPUT NEEDED!