If the FireFox files for saved passwords are corrupted, a System Restore of Windows may be be the only way to restore the damaged files you mentioned. It may be best to reset the saved passwords you need to obtain from the Saved Passwords feature of FireFox instead of doing a System Restore of Windows to view them.
When I want to see the list of my passwords in the saved data in the privacy settings, this is empty. It looks like a damaged key4.db and/or logins.json. I tried to reset FF and import backup, no result. Same with clean FFox installation. Is there anything it can do about it?
Thanks for the advice.