First you need to verify that the Windows Audio Service is running on your computer.
Follow these steps:
1. Click Start, type Services.msc in the Start Search box.
2. Scroll down the list of services, right-click Windows Audio and select Start.
3. Select Properties for Windows Audio and set its Startup Type to Automatic.
If the Windows Audio service does not start and you get the error Error 1068: The dependency service or group failed to start, then make sure that the following services are started and their Startup Type is set to Automatic.
Plug and Play
Multimedia Class Scheduler
Windows Audio Endpoint Builder
After finishing those steps, reboot your system and see what happens.
If the issue is not resolved, try using the Microsoft Fixit Solution Center:
Under option 1 (Select a problem area) Click on the Windows Icon
Next, under option 2 (What are you trying to do ?) Select "Play games, music or sounds, pictures or video"
A new box on the right will appear. Choose "Music or sound"
Now scroll down and you will see a menu of "fixit" options offered.
Choose the second one - "Automatically diagnose and fix Windows audio playback problems"
Click on the "Run Now" tab and allow the fixit to run its course. You will be presented with the results as to whether or not the issue was fixed and, if not, what steps to take next.
Hope this helps - and please do let us know the outcome.