If you're not hearing sound from your computer, it could be related to hardware or a faulty device driver. Before assuming that your sound card is the culprit, take a few simple steps to determine what is wrong.
Restart the computer to refresh the settings. Sometimes performing a system restart will resolve an issue with a sound card.
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Verify that everything is plugged in and is turned on. This includes checking the wires from the speakers to the computer and making sure the speakers have power. Also check to see if the volume isn't muted or turned down extremely low.
Check to see if the driver is working. To do so, navigate to the "Start" menu, right-click on "Computer" and select "Properties." The System Information window is displayed. In the left pane, click the "Device Manager" link. The Device Manager window appears. Expand the "Sound, video and game controllers" section. Double-click on your sound device. The Audio Properties window of your sound device appears, indicating whether your sound card is working properly or not. If it isn't, reinstall the sound card driver. If the sound card doesn't appear, then it might be defective.
Verify whether your speakers are working properly by connecting them to another computer. Alternatively, connect other speakers or headphones to your existing computer to determine whether they work. If the speakers work, the sound card is probably defective.
Before assuming that there is a problem with the sound card, roll Windows back to an earlier date by using System Restore. To do so, navigate to the "Start" menu and type "system restore" (without quotes) in the Search bar. Click "System Restore." The System Restore dialog appears. Click "Next." Click on a Restore Point which has a date a few days before the problem started to happen. Click "Next," then click "Finish" to confirm your Restore Point. After restarting, the system will be restored to an earlier date. Determine whether you hear sound. If so, your problem has been solved. If not, it's time to replace your sound card.