If your Windows sound is not working there could be a number of causes. Below are some tips that may help you fix a number of audio issues.
Windows sound is not working because speakers are muted - This is the simplest of all the steps and a very common reason people report as a cause for sound not working. Instructions cover how to unmute your sounds in Windows and How to tell if Windows sound is set to mute.
Check Windows sound playback device - Your Windows computer may have a various playback devices such as speakers and headphones. These instructions cover how to choose a playback device for your audio. You may have simply selected the wrong playback device.
Check the speaker connection on the back of the computer - Most computers have at least three jacks that connect to sound related hardware on the back of the computer. These instructions help you locate the correct sound line-out jack to get your sound working.
Missing sound card, no sound hardware or sound drivers in device manager - Do you have sound hardware installed? No sound driver? These instructions explain how to identify whether or not you have audio hardware or drivers installed by using Device Manager.
Missing sound drivers in device manager - How to check Windows Device Manager for missing sound drivers indicated by yellow exclamation or question marks and how to update sound drivers.
Find missing sound drivers with Windows Update - How to use Windows Update to find the sound drivers you need to get your sound working again.