Just add your site in Google Webmaster tools. They will analyze your web site and will assist you to clean your files. To avoid this, you can take following action. - Reset your FTP password. - Scan the system for virus/malware/trojan from where you are managing your web site. - Upgrade your third party script to latest version. - If you are using third party theme/template then make sure it is not vulnerable. - Ask your host to check logs for the hacking. - Check all the files which are in your FTP space and remove the malicious files (i.e. phpshell script etc.)