What happened to my sound? ):?

Okay well, something is really wrong with my computer..So, I come on one day, and notice, that my sound wasn't working. So, I looked at the little volume icon in the right of my taskbar. It didn't show muted. So, I clicked on it, and it said this: "There are no active mixer devices available. to install mixer devices, go to control panel, click printers and other hardware, and then click add hardware. This program will now close." I tried what it said, and nothing worked. Could somebody PLEASE help me. Thanks!