1. Click the Start button in the lower-left corner of your computer screen. On the Start menu, select Run. A command screen should pop up.
2. In the command line, type the following: 'services.msc' and press Enter. The services window should now appear with programs listed in alphabetical order.

3. Look down the page, and select 'Windows Audio' and press Enter.
4. In the new window, you will see an option for 'Startup Type.' Be sure this is set to Automatic.
5. Under 'Startup Type,' you will see the line 'Service Status.' Click the Start button.
6. Restart the computer, and the sound should be working again.
7. If this did not fix the problem, there might be another program turned off that also needs to be running. The following programs may need to be started to allow the Windows Audio Service to function properly: Plug and Play, Windows Audio Endpoint Builder, DCOM Server Process Launcher, Remote Procedure Call (RPC), and Multimedia Class Scheduler. Go back and first make sure all of these programs are also running. To do this, repeat the steps listed for the Windows Audio Service for all the programs mentioned, and then restart the computer.