Recovering from hacks is off topic per our FAQ. Use this tag only to solve problems future visitors may have too.
A useful list of first steps after a security breach can be found in this question: Verifying that I have fully removed a WordPress hack?
Find further information here:
- Server Fault: My server's been hacked
- IT Security: Tag WordPress
- Codex: FAQ My site was hacked, FAQ Security and Hardening WordPress
Always keep in mind that your web site is not secure until you found, understood and fixed the way the attacker has used.