Did you back up your Firefox user data or your Firefox Profile before formatting your PC?

no i didn'"t backup it i just sync my profile like i do on google chrome. when i open my account on chrome they recover all my bookmarks but firefox didn't . months of data lost

So, you where using Firefox Sync, you failed to mention that. Firefox Sync wasn't intended to be used in lieu of a backup.

Do you have any other devices connected to your Sync account?

Did you have any problem when connecting to your Firefox Account when attempting to connect to Firefox Sync?

i don't have any device connected with my firefox account

I also have this problem, I had my phone Firefox synced with my pc firefox , when I checked my bookmarks on the phone they were replaced with the ones on the pc, which have nothing but getting started, is there something that can be done

I was wrong I did find my bookmarks on the phone how can I move them to the PC