Sorry, without your Recovery Key / Sync Key your data is useless and can't be retrieved from the Sync Server, That "Key" is the encryption algorithm for your data when that data is off your computer - while traveling across the internet to and from the Sync Server and while on the Sync Server. It is a randomly generated "Key" that only you ever see or have access to.

Sorry to hear that... I was hoping there would be a solution... it is a disappointment to lose all my bookmarks for the past few years :(

The sync key is only used locally to encrypt your data before it is send to the sync server, so without the sync key that data has become useless and couldn't be decrypted even if you could access it (which isn't allowed). You should always immediately make a backup copy of the sync key as soon as you set up a sync account.

• https://support.mozilla.org/kb/ive-lost-my-firefox-sync-account-information

Thank for the reply. I got the point. Guess it is important for users to keep the "recovery key" in a secure way (probably separate from the computer they are using), because if they lose it, there is no way to recover it even with their own sync account ID/password...