Carefully follow FAQ - My Site Was Hacked.
Then take a look at the recommended security measures in Hardening WordPress and Brute Force Attacks
Change all passwords. Scan your own PC. Tell your web host you got hacked; and consider changing to a more secure host: Recommended WordPress Web Hosting
If you can't do the work yourself, consider looking for a reputable person on freelancing sites such as Elance. (FYI, it's not a good idea to respond to unsolicited emails from forum users offering to work for you.)