No Audio out

My friend has a Toshiba Satellite A135-S2276 laptop, it is running Vista SP1. The sound card works fine just for the windows sounds but not a single audio or video player (JetAudio,Winamp,WMP,K-lite..etc) plays correctly. The program is running but no sound is out from the speakers.
What exactly is this? This is the 1st time I face such thing :confused::(

He may not have the right codecs installed. You'll find all that you need here, for free:

K-Lite Codec Pack