text: if it is a built in card, I would suggest looking at the manufacturer's site of the board and model.  It should be an Intel, Asus, or some well known brand if it is a desktop.  If it is a laptop, I would suggest taking it in to a service center and if it is under warranty, to a service center that can do it under warranty.  Another way to fix it is to find the drivers.  Those would also be at the manufacturers site.  Yet another way would be to reinstall windows and hope that windows has its own mixer devices installed correctly.