If the entire Server is deleted, I have no idea how to restore it. If it was just the world of the Server, you can get a backup from last hour at the BACKUPS Tab when your server is running.Then, press RESTORE SERVER.Now, your world should be back in your Server! Your progress from last hour or less might be gone, but you're back, so you can be back where you were within an hour of playing.
I hoped this helped you!