No sound card was found. If one is expected, you should install a sound driver provided by the hardware manufacture

If your computer came with a motherboard disc the sound drivers could be on it
click start control panel administrive tools computer management device manager scroll to sound,video and game controllers you might see a yellow question mark? Right click to reinstall drivers if you dont have a motherboard disc you will have to download the drivers

http://download.cnet.com/Realtek-AC-97-Driver-Windows-Vista-Windows-7/3000-2120_4-10962344.html
Realtek AC'97 audio driver package. The package includes: driver setup program, drivers for Vista/Windows 7 32-bit and 64-bit editions.
hope this helps

http://download.cnet.com/Realtek-AC-97-Driver-Windows-Vista-Windows-7/3000-2120_4-10962344.html
Update your embedded sound from Realtek to the latest AC'97 codec.
if your computer came with a motherboard disc the sound drivers could be on it
click start control panel administrive tools computer management device manager scroll to sound,video and game controllers you might see a yellow question mark? Right click to reinstall drivers or you can download the drivers

Download the driver software by

http://download.cnet.com/Realtek-High-Definition-Audio-Codec-Windows-Vista-Windows-7-32-bit/3000-2120_4-10788600.html free sound drivers

http://www.boxdrivers.com

using this link you will be able select your drivers

hope this helps