First things first, do not panic.
This article will guide you through the process of cleaning a hacked WordPress website. The process is documented in an easy to follow step by step format; identifying the source of the hack, identifying the infection, cleaning the code, regaining control of your WordPress website or blog and removing the Google malware alert. This guide will help you recover from the typical WordPress hacks such as backdoors, malware, spam and other similar types of infections.
Source : wpwhitesecurity