Problems with Sound Card

Hello frens,

I am having problem with sound in my PC. My inbuilt sound card is Sigmatel and is well installed. Whenever I try to play music or any sound file, it plays well but there is no output from the card. I tested with every possible things such as microphone, woofer.

I tried if there's wrong with my my cable but that was not the case. I checked every possibilities, BIOS informed audio enabled, device manager Audio device installed, media player plays sound well EXCEPT I hear no sound from my speakers (which work fine with my other audio devices including woofer).

I didn't listened music for around 2 months. Later I find myself disappointed @ just watching movie video with no audio. Please, help. Is there anything I can do without installing another external sound card? Which are and How much does good quality sound cards costs?

Waitng for your responses!