Site Hacked

Hello,

I was wondering if somebody could help me.

I understand millions of wordpress sites have been hacked through the recent botnet attack and brute force. I believe that my site has become a victim of this.

I loaded my site up to find 2 php errors saying that the required functions.php file was not found and was removed.

After investigating I then found a file called wp-BACK.php and users.php which the hackers used to gain access to my server, change passwords, access databases and modify files.

Has anybody else had the same issue and what should I do?

Thanks,
Dan