To enable the sound, you need to check the situation of the drivers using Device Manager (Start > Right click "Computer" > Properties > (Hardware Tab)> Device Manager). If you have any yellow exclamation marks next to your sound-card, then you might need to re-install the drivers. Alternatively, it's also possible the the service which operates the sound in your computer is stopped and needs restarting. Go to Start > Run > type services.msc and locate Windows Audio in the list. Click on Restart and then check the sound.
