bookmarks

If you didn't locally backup to a USB drive or didn't use Sync connections there are high changes reinstalling your OS wipe clean any data that was on the system at that time. If so then no data recovery is possible now.

Hi Glenn, do you sign Firefox in to your Mozilla account? If you signed the new installation of Firefox in to the same Mozilla account as the old installation, then Sync should download the bookmarks from the Sync cloud in the background.

That process is not perfect. You can check what data is in the Sync cloud for your Mozilla Account using the About Sync add-on:

https://addons.mozilla.org/firefox/addon/about-sync/

After you install the add-on, you can type or paste about:sync in the address bar and press Enter to load it. The page shows each category of data currently found in the Sync cloud.

Anything useful under bookmarks?

If not...

When Windows was reinstalled/reset/refreshed, was ANY of your data preserved? Sometimes this could involve creating temporary folder named

C:\Windows.old

That's usually a temporary folder which gets deleted after 28 days. If you find it, turn on viewing of hidden files and folders --

https://support.microsoft.com/en-us/windows/view-hidden-files-and-folders-in-windows-97fbc472-c603-9d90-91d0-1166d1d9f4b5

-- and explore up the path to

C:\Windows.old\Users\<username>\AppData\Roaming\Mozilla\Firefox

Is there data there? If so, we can suggest how to restore this to the new locations.