Hi… Sorry to hear you’ve been having trouble, 
… If it was a single-Machine database, then the following is generally the resolution:
https://fly.io/docs/postgres/managing/backup-and-restore/#restoring-from-a-snapshot
(Many people have used it successfully in the past.)
Otherwise, it’s best to restore from one of the surviving replicas, using the volume-forking technique (with explicit volume ID).
Or, if you did attempt one of those already, it would be prudent to post the exact command that you tried as well as the full error message that you got in return. The </> button in the toolbar can be used to get an area suitable for pasting code, terminal output, etc.
Hope this helps!
Aside: This recent thread on eze specifically might also turn out to be relevant:
https://community.fly.io/t/failed-to-create-volume-no-capacity-available-in-eze/25509