When I click any category, I get page not found.

I was looking at the support forms and read this post.. I am not a developer for this theme.. Im a user like you are..

The error is in the link you have.. meaning if you mouse over the link you can see at the bottom url ..
http://www.oyuncuspartan.com/http:/www.oyuncuspartan.com/?cat=4/bunlari-kacirmayin/

its hitting your url twice.. I believe all you have to do is type in the full url in your link page and it should work. I had this issue before with themes.. its really a simply fix..
your page does work if you go here.

http://www.oyuncuspartan.com/?cat=4/haberler/