Sound card

[LaloHao]

My computer's been having sound problems since i can remember.
First sympthon was: sound volume was at like half its power, i had it at 100% and it would be as if it was on 50% volume, and and i know this because my brother has a computer same model as this one.
Then: when i was listenning to music sound would crash, it would be as if it was a damaged cd, just looping the last seconds of the sound
Then it just died finally i guess, my sound just doesn't work anymore

This just happened recently, what do you think i can do guys?

[LaloHao]

BUMP
Forgot to say i got Vista 64 bits, does anyone have an idea what might be my problem?