Reply to No sound from headphones

Im using traktor 2 with the kontrol s4 and when i hit the cue button there is no audio from my headphones. Everything was working fine until a couple days ago but i didn't change anything. Also sometimes my laptop will shutdown while using the s4? (usually about 20/30 mins after i start) and when i start it back up there is no response from the s4.

Any help would be much appreciated.