Server hacked

[m0rpheu5@]

Hello guys, in this weekend i got 2 servers linux hacked. The OS is Fedora Core 4, with Plesk 8.1.1 both are hacked, and the hackers changes the password from root, into a server i got problem with mysql and the another mysql and apache, what i have to do? and the worst, the hacker delete all of my backup from my ftp backup, i have access only from Plesk.

Please help me.