Help! My league wont start!!!

When ever I try to load into a game, it shows a black screen, and then doesn't do anything. I then Ctrl Alt Delete and shut down league, which then it gives me this message An unknown DirectX error has occurred and League of Legends cannot start. Please make sure your video card is using the latest video drivers from the manufacturer. I have updated all my drviers, and I have tried reinstalling league! Please help, as I have already been counted for 1 leave on my account! Help me before takes over my account a feeds!