No sound in game.

I have windows 8.1 and I suddenly can't hear any ingame sounds at all. It started 2 days ago. I have sound on my other applications like youtube, itunes, etc. The volume mixer is all the way up and the in game volume too. Also, normally when you enable visual alerts, it would show you the sound effects on the side. I have no effects when this problem occurs. On a side note, when I try to exit the game the game turns to a black screen and makes me force close the program through task manager which is annoying lol.