My screen went black

Hi all,

My iPhone 4 screen suddenly went black. The phone did not fall, or was in contact with coin, keys, nothing of the sort. It´s off as when there is no battery, but the battery was fully charged.

I tried to make someone call me, and the phone doesn´t ring.

I tried to connect it to the PC, and iTunes doesn´t lauch automatically (as if nothing had been plugged in). I totally looks as if it were off. And I cannot turn it on.

Has anyone had this same problem? Or does anyone know if it´s something fixable somehow?

Thanks for the help!