It starts with drumms, then bass and after that they sing na nanana nanana nanananananana (or lalala.. I'm not sure)... the leader of the band is wearing hat like a magician and there are lots of hot girls in video tooo... Please help me find out! Thanks

Sounds like Fall Out Boy. Not too sure, maybe This Ain't A Scene, It's An Arms Race or Thanks For the Memories.. Only working on the magicians hat. Hope this helps

Or Panic at the Disco.. but then I may be way off.. Can't think of anyone else in a magicians hat