Black screen after champion selection

League was running fine until today. After a game of league i started another game. After champion selection when the loading screen should appear, the screen was just pitch black so i tried to get out of it holding alt + tab which i got a pop up tab? Saying it got disconncected and stuff saying if i would like to retry or cancel. It still doesnt work even if i retry and if i press cancel it says my game got crashed. I reinstalled the game but it still doesnt work. Any solutions to this problem?