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.

malcolmord said

I have lost my saved logins

What about the rest of your profile? settings, bookmarks . . . . . Are you using any password add-ons/programs?

You can create a backup copy of the logins.json and key4.db files in the profile folder.

• 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

Are only the passwords lost ? Are you still using the same profile or did Firefox refresh and created a new profile? When Firefox refreshes then it appends a time stamp to the folder name.

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:preferences page.

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

Thanks for the helpful replies. These will enable me to recover any future losses but I still don't know how the loss happens in the first place.

When do you notice the passwords are missing? At startup, while surfing, running disk cleaners . . . .

Are you connected to Sync?