I HAVE A BLACK SCREEN AND DON't KNOW WHAT TO DO IPHONE 4?

I was playing soccer and when i came to my house my iphone was off i though it was dead so i left it charging and i took a shower and i came back and its still off i tried to turn it on but nothing happens my brother has been calling me and he says that the call does work?! What happen to my phone? How can i fix it?

: I know i ask alot of questions but its because a have alot of problems. :V

It sounds like just the screen went out? I would take it to an apple store. If your contract is up then I would just trade it in and upgrade as 4S is free on a 2 year contract, so you would get a free upgrade and even some credit back for the 4.