If you were logged into firefox then it may have synced your bookmarks. You can check if this is the case by visiting the 'sync' tab.

If you reset the password of the Sync account then you lose all data stored on the Sync server. This is because this password is used to encrypt your data locally before it is uploaded to the sync server and only this data can be used to decrypt this data. You can generate a recovery key and store that in a safe place that you can use to get access to your Sync data, but if you would do the same with the password then you wouldn't need the recovery key.

• https://support.mozilla.org/en-US/kb/reset-your-firefox-account-password-recovery-keys