Oh dear, well lets get to work:

You can try to restore a previous version of the signons.sqlite file. (password file)

   Right-click: Properties > Previous Versions
   http://windows.microsoft.com/en-US/windows7/Previous-versions-of-files-frequently-asked-questions 

You can use this button to go to the Firefox profile folder:

   Help > Troubleshooting Information > Profile Directory: Show Folder (Linux: Open Directory; Mac: Show in Finder) 

   http://kb.mozillazine.org/Password_Manager
   http://kb.mozillazine.org/Profile_folder_-_Firefox 

Hope this helps Brad

Firefox 32 and later builds store the passwords in the logins.json file in the profile folder and no longer use the signons.sqlite file that has been used before (the matching key3.db file is still needed). So you would need a backup copy of that file.

If you have a copy of signons.sqlite file and the corresponding key3.db file then you can try to force Firefox to migrate passwords saved in this file (you will lose passwords saved in logins.json). You can force Firefox to reimport the passwords from the signons.sqlite file and rebuild the logins.json file with these steps:

• reset the signon.importedFromSqlite pref on the about:config page to the default value via the right-click context menu
• delete the logins.json file in the Firefox profile folder with Firefox closed

When you restart Firefox then you should have the signon.importedFromSqlite pref with the value set to true and you should have the passwords imported in the Password Manager unless there may have been errors.