i cant see anything in my crossfire

i cant play cross fire because at first it was all the same and perfect but whenever i'm joining in the game i cant see anything all i can see is a black screen with names of the players and and map on the upper right side of the screen. i can walk and fire my gun but i cant see anything all i can see is black. but i played crosfire last night and it was . but today i cant play it anymore