Look on your desktop. Do you see a folder called; Old Firefox? Look inside.
Look for the folder with the latest creation date.

https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

http://kb.mozillazine.org/Profile_folder_-_Firefox#Navigating_to_the_profile_folder

https://support.mozilla.org/en-US/kb/profile-manager-create-and-remove-firefox-profiles

https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Type about:profiles<enter> in the address bar.
How many profiles are listed?
How many should be there?
Also, open the profile folder in your file explorer.

Do you have a recent upgrade.jsonlz4-<build_id> in the sessionstore-backups folder in the profile folder?

You can use the button on the "Help -> Troubleshooting Information" (about:support) page to go to the current Firefox profile folder or use the about:profiles page.

• Help -> Troubleshooting Information -> Profile Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

Backup the session files in the sessionstore-backups folder in the Firefox Profile Folder to make sure not to lose possible important session data. Do NOT close Firefox when Firefox is already running.

You will normally find these files in the sessionstore-backups folder:

• previous.jsonlz4 (cleanBackup: copy of sessionstore.jsonlz4 from previous session that was loaded successfully)
• recovery.jsonlz4 (latest version of sessionstore.jsonlz4 written during runtime)
• recovery.baklz4 (previous version of sessionstore.jsonlz4 written during runtime)
• upgrade.jsonlz4-<build_id> (backup created during an upgrade of Firefox)

You can copy a file from the sessionstore-backups folder to the main profile and rename the file to sessionstore.jsonlz4 to replace the current file (make sure to backup the current sessionstore.jsonlz4).

FredMcD - THANK YOU!!! I did the first thing on the list -- the about:profile search, and it had an old one that opened up all of my stuff!!

I'm curious, though -- now the old one says this: Profile: default This profile is in use in another application and it cannot be deleted.

And the updated version says this: Profile: default-release This is the profile in use and it cannot be deleted.

So are they both in use?

I wonder if I should close them all and open them all and see if I still get to use my old, saved data? And then I'm curious if I should backup my bookmarks n things?

Anyway - THANK YOU for taking the time to answer my question!! cheers, Jenny

Reboot the computer. Is the problem still there?

You're my hero! I re-booted and it worked. Such a relief. So I'm curious if I am operating on the updated firefox with my old info, or am I now using the old firefox?

Thank you again for your time and support -- such kindness is inspiring. cheers, Jenny

Note: Firefox comes in three or more folders on all computers. They are;

Maintenance: (Programs Folder) <Windows Only>
Firefox itself: (Programs Folder)
And two folders in the profile of each user on the computer for each Firefox profile for that user.

If you remove the Firefox folder, the user profiles would not be affected.

I am glad to hear that your problem has been resolved. If you haven't already, please select the answer that solves the problem. This will help other users with similar problems find the solution.

Thank you for contacting Mozilla Support.

Thank you, again! :)