Check the computers Recycle bin. Your passwords are stored in the key3.db and logins.json files.

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.

These can't get your data back, but will help in the future.

These add-ons can be a great help by backing up and restoring Firefox

FEBE (Firefox Environment Backup Extension) {web link} FEBE allows you to quickly and easily backup your Firefox extensions, history, passwords, and more. In fact, it goes beyond just backing up -- It will actually rebuild your saved files individually into installable .xpi files. It will also make backup of files that you choose.

OPIE {web link} Import/Export extension preferences

How did you delete the logins?

Do you have any backups of your currently active Firefox profile folder that might have older versions of the files?

Here is a thread with potential methods of using Windows restore points to find old versions of the critical files. These steps were for Windows 7 and did not work on Windows 8-8.1, but I don't know whether anyone has tried them on Windows 10 yet: Can I undelte saved passwords in v 38.0.5?

You could check if there is still a signons.sqlite file in the Firefox profile folder.

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

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

If you have a copy of the signons.sqlite file and haven't changed the master password (so key3.db is still valid) 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.