No Sound In computer after Installing Windows 7
Right-click the speaker icon on your taskbar.
and then Select Playback Devices.
To ensure all the devices are listed, Right click in the Empty space in the Playback tab and make sure that both Show Disconnected Devices and Show Disabled Devices are selected.
If you see New icons for the Speakers and Microphones you want, set them as Default by clicking on the Set Default button.
That ought to do it.