I gather you found oldfirefoxprofile on the Desktop your passwords/logins are in :

• logins.json (passwords) and key4.db (58+) or key3.db (57 and older) (decryption key) for Passwords saved in the Password Manager
• if you only have key3.db then make sure to remove an existing key4.db

You can copy files like these with Firefox closed to the current profile folder to recover specific data.

• https://support.mozilla.org/en-US/kb/recovering-important-data-from-an-old-profile

fyi for the future :

• https://support.mozilla.org/en-US/kb/export-firefox-bookmarks-to-backup-or-transfer
• https://support.mozilla.org/en-US/kb/back-and-restore-information-firefox-profiles

Please let us know if this solved your issue or if need further assistance.

I can search and find key3 and 4, but neither will open. I get a message that the files are unsupported

If not have a folder on the Desktop Called OldFirefoxProfile Searching is going to turn up your current Profile unless there are 2 Profile Folders and would be looking for the one with the oldest date.

• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

If not there then they are gone.

i find the folder, and the key 3 and 4 .db but what do I do with them?

You do not open key#.db files. You need to copy logins.json and key4.db to the current profile folder with Firefox closed to recover passwords.

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:profiles page.

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