Hi, a change to Profiles was made in Firefox 67 and this shouldn't have happened - but you are not alone! Check whether your data is available in a different profile:

Inside Firefox, type or paste about:profiles in the address bar and press Enter/Return to load it. The About Profiles page will open. This page should list at least one profile and could list many.

The profile that Firefox is currently using will show:
This is the profile in use and it cannot be deleted.

Please do not delete anything here; don't use any Remove buttons.

Do you have another profile named default or default-longnumber listed on this page? If so, you can check whether it is the one you were using recently by clicking its Launch profile in new browser button.

If it isn't what you want, simply close that new window.

If it IS what you want, click the Set as default profile button for that profile on the about:profiles page. Firefox will use it automatically at the next startup.

Note: If your bookmarks are not available in another Firefox profile, see Recover lost or missing Bookmarks for other solutions.

If your question is resolved by this or another answer, please help other users by marking the best reply as Solved. Thank you!

I've tried this already and it shows only two profiles, none of which have any of my data. But there could potentially be two more from what I can see when I go through my files on my laptop. I've also already tried the bookmark thing and nothing shows up under 'restore'.

Try restarting Firefox. If that doesn't work, restart your PC.

Restarting didn't do anything

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

I can't find 'old profiles' anywhere, only 'profiles' in two different locations, C:\Users\Betty\AppData\Roaming\Mozilla and C:\Users\Betty\AppData\Local\Mozilla. Both have a 'profiles' folder with what looks like the same data in them.

So I've played around a bit and copied all the data I've had in one of the profile folders (that looked like it could be the right one) into a new profile that I made up and it worked, everything is back now! Thanks for the help!

Glad to help. Safe Surfing.

Back up and restore information in Firefox profiles.{web link} I use an add-on that makes backups of my user profile, Just In Case. Unfortunately, it is not compatible with the current Firefox.

Every now and then, open the profile folder and create a copy of the current profile as is to another location on your hard drive. This way you will have a backup.

If you do this each day, you will not lose much data. This should be done with Firefox Closed.

Note: In case you need to restore from these backups, you may need to overwrite old or corrupted files.