What about the rest of your profile? Settings, bookmarks, history, passwords . . . .

Try rebooting your system.

In the event that the passwords information is lost, you should record all information in a separate text file somewhere else on your hard drive, or written down. You can easily copy and paste if you need to do so. If you are concerned about someone else looking at that file, you can compress it using a password.

All of my other profile information including bookmarks and other information is still there, but the passwords are completely gone. First thing this morning, I noticed immediately because when I logged into a site, it didn't autofill, so I rebooted my computer twice.

Weird update to my post. Now all of a sudden, an older version of my passwords are back on Firefox. For example a site I use every day, has a password and login from two years ago. It's like all of a sudden Firefox reinstated an old backup. I did nothing as far as that is concerned as I have just been logging into various sites I used everyday.

That is very odd. Are you sure you are using the same profile?

In the event that the passwords information is lost, you should record all information in a separate text file somewhere else on your hard drive, or written down. You can easily copy and paste if you need to do so. If you are concerned about someone else looking at that file, you can compress it using a password.

Back up and restore information in Firefox profiles {web link} I use a Legacy 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.