Do you have an "Old Firefox Data" folder on the desktop?

When you Refresh/Reset Firefox then a new profile is created and some personal data (bookmarks, history, cookies, passwords, form data) is automatically imported. The current profile folder will be moved to an "Old Firefox Data" folder on the desktop. Installed extensions and other customizations (toolbars, prefs) that you have made are lost and need to be redone.

You can use one of these to make Firefox create a new default profile or recover an existing profile:

• Delete the profiles.ini file to make Firefox create a new (default) profile
• Use the Profile Manager to create a new profile
  If you still have an existing profile then click "Choose Folder" in the Profile Manager and browse to the location of a lost profile to recover this profile
  https://support.mozilla.org/kb/Managing+profiles

You should find the profiles.ini file in this hidden location:

• Windows: %AppData%\Mozilla\Firefox\
  *C:\Users\<user>\AppData\Roaming\Mozilla\Firefox\
• Mac: ~/Library/Application Support/Firefox/
• Linux: ~/.mozilla/firefox/

If clearing the profiles.ini file isn't working then also check the location of the cache files.

• Windows: *C:\Users\<user>\AppData\Local\Mozilla\Firefox\Profiles\<profile>\
• Mac: ~/Library/Caches/Firefox/Profiles/
• Linux:~/.cache/mozilla/firefox/

You can also try to rename/delete the MozillaFirefox folder in both above mentioned locations (main, cache).

• http://kb.mozillazine.org/Profile_Manager
• https://support.mozilla.org/kb/Managing+profiles
• http://kb.mozillazine.org/Profile_folder_-_Firefox

Thanks.......

   Completely by chance, I I discovered the User's Library is HIDDEN!!! from the Finder View.   Once in there, I was able to use your valuable instructions.
    Search results in the Macintosh Finder do not return location of the User's Library or any sub folders within, for instance -  the Firefox Folder or the Application Support.  This renders your instructions as cryptic and confusing.
    If I may possibly suggest some inclusion in your instructions as to the location of the Users Library, it would be very helpful for the average user.  
   Many thanks.

Completely by chance, I I discovered the User's Library is HIDDEN!! from the Finder View. Once in there, I was able to use your valuable instructions.

    Search results in the Macintosh Finder do not return 

location of the User's Library or any sub folders within, for instance - the Firefox Folder or the Application Support. This renders your instructions as cryptic

and confusing.

    If I may possibly suggest some inclusion in your instructions as to 

the location of the Users Library, it would be very helpful for the average user.

   Many thanks.

To LOCATE USER LIBRARY: From the FINDER GO menu - choose Command_Shift_G. Then type destination folder (LIBRARY) or APPLICATION SUPPORT

See also:

• http://kb.mozillazine.org/Show_hidden_files_and_folders#Mac_OS_X