You can't restore a forgotten Primary Password. You can reset this password, but you will lose all passwords currently stored in the Password Manager (Lockwise).

• https://support.mozilla.org/en-US/kb/reset-your-primary-password-if-youve-forgotten-it

You may want to keep a backup copy on logins.json and key4.db in case you remember the primary password.

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 Folder/Directory:
  Windows: Open Folder; Linux: Open Directory; Mac: Show in Finder
• https://support.mozilla.org/en-US/kb/profiles-where-firefox-stores-user-data

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.

I made the mistake of setting a primary password, and made sure to write it down, but when I tried to enter it, I got an error message "invalid password". Now what?