NO sound is coming from my laptop

Hello,

I have a Dell latitude D520, and a couple of days ago the volume was just working fine, now there is no sound coming from laptop what so ever. All of the volume controls turned up and nothing is on Mute. So what should be my next move? Also I looked in the hard drive folder and saw a folder that said volume system control but the folder wasnt accessible. So I would appreciate it if i could get a response as soon as possible!
Thanx in Advance!