No Audio Output Device is installed

Hi,

I have a compaq presario V6500 which came installed with Windows Vista. I recently upgraded my OS to Windows 8 (last month). Today, just like that, the sound was lost, while I was listening to a tutorial online. The sound icon on the desktop taskbar says "No Audio Output Device is installed". When I trouble shoot it, by clicking on it, I get these messages, and no other solution-


I went into Device Manager and tried to figure out whats wrong. Under "Other devices", I see an exclamation with "Coprocessor". When I click on it, this is what I see-

Device type: Other devices
Manufacturer: Unknown
Location: PCI bus 0, device 1, function 3
Device Status: The drivers for this device are not installed. (Code 28) To find a driver for this device, click Update Driver.

When I click Update Driver, windows is not able to find a driver (even online).

I also cannot see any icon for sound/audio devices under Device Manager.

I'm not sure what to do about this. I'm not very tech savvy. Can someone help me out with this problem?

Thank you!

As this just happened, use the System Restore function and restore the PC back to an available restore date when it worked OK.

The coprocessor is a separate issue and most likely not related to sound.

How do I do System Restore in Windows 8?

Hold the Windows Key Down and Press the Pause/Break Key. In the System Panel that comes up, Click "System Protection". System Restore can be accessed from the Panel that comes up.

There are a couple of other ways, but this one works.