No Sound System Installed On Windows..?

Hello,

Okay, So I have a Windows Vista, and I've tried the reinstalling the device, restarting my computer, checking to see if it's not installed or just muted...nothings working. I've even disabled and enabled! I didn't mess with any of my programs or computers the day before this happened, and now I cant find out how to fix it!
Any Ideas would be really helpful right now, Thanks alot

Oh and my sound proccesor, incase this helps anyone, is a Sigma Tel High Definition Audio...