Did you open the Password Manager to see if the data was there? Is the manager set to remember logins?

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.

Look on your desktop. Do you see a folder called; Old Firefox? Look inside. Look for the folder with the latest creation date.

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

https://support.mozilla.org/en-US/kb/how-run-firefox-when-profile-missing-inaccessible

Thank you for response. I'm using a latvian version of Firefox, but I think yes, that is password manager- tab called "security" in page detail menu. So yes, I opened password manager and there was no these passwords stored. NEVERTHELESS I was able to fill username fields with these usernames. With no passwords in Password Manager [it was completely empty- no usernames and no passwords].

Of course, I'm storing my passwords, but not on this particular computer, that is not the case. Problem is they simply disappeared right after a last update.

There are no folder on my Desktop called "Old Firefox". There never was something like that after an automated Firefox update.