Go to the Start Menu, and right click on 'My Computer.' Click Properties.
CLick the Hardware tab, and then a Button that Says 'Device Manager.' On some operating systems, you'll simply have to click on a Device Manager Tab.
Look for an item in the list that either says 'Sound Device,' 'Sound, game, and video controllers,' or something with sound or audio in it. Click the + sign beside it.
If it has a device, look at it. This is your sound card. If it has a yellow symbol beside the device, tell us so.
If you open up device manager, and the first thing you see is a device with a yellow symbol, say so.
Post please, and use real words.