Hacked ... what to do next ???

Hello to all habroos and habroinoplonetyanam!

Recently - or rather, last summer I opened a website dedicated to the automotive theme, namely the traffic police video cameras. About him wrote on Habré . So - yesterday I ran into such a nasty thing - like hacking the site. Who and why it took to break - now I do not really want to understand. The motives may be completely different from hooliganism, to warning - after all, the site is still more antisocial.
')
I would like to ask your advice.
What should I do next? I picked up the site again, checked everything.
BUT WHAT DO NEXT? Write letters, but to whom and where?
ATS, MVD, FSB - in general, what kind of power structure is responsible for such things?

I really do not want to repeat)

Thank you very much for the help.