Vista - Hi, Help Please

Hi, my vista laptop home premium, Compaq is like 14 months old.

About a month ago my sound has been not good like the sound wasnt good quality sound it just sounded bad.

Anyways now, I have no sound at all, I put my cursor on the sound thing at bottom it says..."No Audio Output Device Is Installed"

But randomly everyonce in a while the sound works, not good quality though, and if im watching a youtube video it would stop randomly in, also on Firefox sometimes I watch myspace or ESPN videos, my firefox would not respond to it.

So if anyone knows how to fix this, I have tried other forums and people say.

" Go to Hardware and Sound and find the Gaming Application thing or something like that...theres nothing in there"..

Also that my sound card is just completely fried..

Well thanks.

Up help please