So I downloaded the security update for 3.3.x and just after that my site got attacked.

My web host managed to stop him in time, apparantly one of the admin who has restricted admin access got keylogged.

Now my modcp / admincp has gone missing and my user options are gone too.

I googled this problem, there are sayings that it's cracked. I'm uncertain on what to do now. :S

You should submit a ticket. You probably got demoted by the hacker.

just go into your ftp and put ur self back as a admin