Sound card

Try pulling the card & clean the slot it was in. Use canned air & or a very clean dry paint brush. Than get a soft clean cloth & lightly dampen it with Alcohol, wipe the cards copper connectors. Make sure it is dry before reinstalling. Press firmly & evenly down make sure it is seated. Fire up the pc & enter the control panel, open Sound & audio devices. Click the Audio tab & check that there is a device listed in the window. Do the same click the Voice tab, it should list the same device. If you saw a listed decive & still have no sound. Close Sound & audio devices & open System. System properties will open, click Hardware tab & than click device manager. Scroll down to Sound, video & game controller. See a yellow ! point. You need to reinstall your sound drivers. No ! point. Than your card is dead. Try replacing it. Hope it works out!
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1. Right Click My Computer and left click properties.
2. Click Hardware
3. Click Device Manager
4. Click the plus (+) sign next to Sound Video and Game
5. Right click on Realtek or AC97 or what ever is your sound card and delete
6. Restart and allow windows to find sound