If you were using Firefox sync, you can try signing into sync on your new installation of Firefox and your bookmarks may be recovered. However, Firefox sync was never designed to be a backup system, so it may not be successful in recovering data 100% of the time.

Unfortunately, if your Firefox data was on the drive that was reformatted, this data can no longer be retrieved.

In the future, we recommend backing up your Firefox data periodically (especially before a reformat). For more information on how to backup your Firefox data, please refer to this Mozilla support article:

• Back up and restore information in Firefox profiles

Sorry for any inconvenience caused by this issue.

Sounds like you didn't back up your bookmarks before formatting your hard drive. Silly mistake.

If you were using Sync prior to that formatting episode, you might be able to recover your Firefox data as long as you know your Username (email address) and the Password that you were using. See Connect additional devices to Sync in this support article: https://support.mozilla.org/en-US/kb/how-do-i-set-sync-my-computer#w_connect-additional-devices-to-sync

If you Reset the Password for Sync / Firefox Accounts - your data is gone. That is a fatal mistake.

Keep in mind that Sync isn't designed to be used as a backup device, but merely to sync data between multiple devices. It is not guaranteed that you can restore data from the Sync server in case of problems with your OS or because you otherwise lost data. Requesting a new password because you forgot it or changing the password for the Firefox Sync account will wipe all data stored on the Sync server and you won't be able to retrieve data that was stored previously. Best is always to backup your personal data locally to be sure to be able to recover from issues.

• http://kb.mozillazine.org/Profile_backup
• https://support.mozilla.org/kb/Backing+up+your+information