Problem!!!! Black screen after champion selection Please help!!!!!!!!!!!

After champion selection i have a black screen. When the loading screen appears and also when im enterring in the game. I still can hear the sound and move my character but i dont have image just a black screen! Please help me . The launcher works i can do whatever i want its just i wanna play.

-Window 7

But the weird thing is its doing also on dota 2( ive install it to see if it was my computer or the game problem)