Hi Petra, I don't think you can create recovery keys if you cannot log in to the account...

However, if you still have your old computer, you can move over Firefox's data files: they are all stored locally on disk. Is that still possible?

Thanks for your quick answer! I just saved all the bookmarks (they were the most important files) and transferred them to my new laptop. I saved that file, so I can use it to install it again after I changed my password. Thank you!

I would like to add, that after creating a new password all my settings were still there. So nothing bad happened :-) Now I am going to create a recovery key ;-)

You can copy certain files with Firefox closed to the current profile folder to transfer or recover personal data. Note that best is to avoid copying a full profile folder.

• bookmarks and history: places.sqlite
• favicons: favicons.sqlite
• bookmark backups: compressed .jsonlz4 JSON backups in the bookmarkbackups folder
• cookies.sqlite for the Cookies
• formhistory.sqlite for saved autocomplete Form Data
• logins.json (encrypted logins;32+) and key4.db (decryption key;58+) for Passwords saved in the Password Manager
  key3.db support ended in 73+; to use key3.db in 58-72, make sure to remove key4.db
• cert9.db (58+) for (intermediate) certificates stored in the Certificate Manager
• persdict.dat for words added to the spell checker dictionary
• permissions.sqlite for Permissions and possibly content-prefs.sqlite for other website specific data (Site Preferences)
• sessionstore.jsonlz4 for open tabs and pinned tabs (see also the sessionstore-backups folder)