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

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.

Close, then reboot the computer.

Everything else - bookmarks, settings, and history - remained the same. Only the saved passwords disappeared. Unfortunately, closing everything and rebooting did not help.

I'll start creating a file of passwords. Thanks.

What security software do you have (possibly AVG/Avast?) ?

You can check the profile folder to see if there are logins.json.corrupt files present. If you find such a file then try to rename to logins.json with Firefox closed.

• keep a backup copy of all logins.json files

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 Directory:
  Windows: Show Folder; Linux: Open Directory; Mac: Show in Finder
• http://kb.mozillazine.org/Profile_folder_-_Firefox

I use AVG. I changed the logins.json file and everything is back to normal now.

Thank you very much.

You're welcome.

See also:

• https://support.mozilla.org/en-US/kb/passwords-disappearing-avg-security-software

Mozilla created an extension to recover logins.json from a logins.json.corrupt file.

• https://addons.mozilla.org/firefox/addon/restore-logins/