If you reset your Firefox Account password without using your account recovery key, you lose access to any Firefox Sync data that was on the account. Unfortunately, this is a technical restriction that can't be bypassed. When you send data to the Firefox Sync server it's encrypted so that other people can't see what that data is. It's encrypted using the account password. The information is decrypted again with the same account password. If your password on your account changes, it no longer matches the password needed to decrypt the existing data, so that data become unusable. Contrary to what a lot of people think, a (properly designed) website doesn't actually save a copy of your password on your account. Instead, a ''hashed'' copy of your password is saved on the account system. Hashing converts your password into seemingly random text, which means that people can't hack into the system and see what your password is. Each time you log in, the password you enter is hashed and that hashed copy is compared to the hashed copy that's on the login server. Since the Firefox Account system doesn't actually have a saved copy of your account password, it can't change existing information to use the new password, since it would need to know the old password to first decrypt the data and then encrypt it with the new password.