Hi… For Managed Postgres, you would just need to file a support ticket.
(Look in “Managed Postgres” versus “Legacy Postgres” in the dashboard, to see which you have.)
Legacy Postgres, in contrast, was always intended to be managed by the user, although not everyone realized that when they were signing up. Basically, you are your own DB sysadmin. If this is multi-node Legacy Postgres then you should, with that hat on, be able to recover immediately, since the surviving nodes still have all the data.
For single-node Legacy Postgres, you might be able to recover from the streaming backups, if you had those enabled. If not, then there’s unfortunately a choice between (a) waiting in the hopes of successful hardware repair or (b) getting back up and running now with some data loss. The automatic volume snapshots occur every ~24 hours, but if you have a more recent pg_dump, or similar, then you should use that instead.
These maintenance periods can last a very long time—and may end with the entire physical host machine being lost in the end. (The Fly.io infrastructure staff can’t always tell the timing or the probable outcome in advance.)
In general, the single-node Legacy Postgres databases shouldn’t be used for production on the Fly.io platform, although obviously the temptation is understandable.
Single-node databases other than Fly Postgres would typically have similar caveats.
Hope this helps!