To update your sound. Windows XP
Start - control panel - open system icon - Hardware Tab - Device manager -
Click the plus sign for sound and video.
Right click your sound (whatever your using) - properties - update drivers -
and follow the directions.
You will need the CD that came with your computer.
Or get your sound driver from the Internet.

Start - All Programs - Accessories - System Tools - System Information
See if it has your sound listed. What kind.

See if your sound has been stopped in Services Under
Windows Audio.
Start - Control Panel - Open Administrative Tools - Click Services and Scrowl down the list to
Windows Audio to see if it says - Started. If stopped
Left click Windows Audio and click restart. -
Or
Right click Windows Audio - left click Properties - Left click Start.

While in Services check to see if Plug and Play is Started.