Hi JohnieKul, could you mention what OS is running on the computer? Your post is currently under Android but it sounds as though the issue would be on MacOS, Windows, or Linux.

Did your new installation of Firefox pick up any settings from your Sync account at all?

Do you still have access to the old computer to copy files from?

I do not have the old computer, was using Mac Os.

As Jefferson asked "Did your new installation of Firefox pick up any settings from your Sync account at all?"

If nothing was sync'd to that new computer I would say your data is lost. Sorry for the loss of your bookmarks. Sync was not intended to be used with a solitary device in lieu of a proper backup; it was created to synchronize Firefox data across 2 or more devices.

The main difference being that when one device would be replaced the users data would still be on another device, and not just on the Sync server. A major misunderstanding about Sync is that user data residing on the Sync server is encrypted via dual keys that are created from the user set password for the Firefox Account; if or when the password is changed a different set of keys are needed to decrypt the users data. So when the password is changed the user data for that account is cleared, as that data 'blob' is rendered useless. IMO, the encryption method used is a way "over the top" for all but Login data.