If your Windows sound is not working, it’s a good idea to verify that your computer has sound hardware such as a sound card or other audio components. This can be checked by opening Device Manager.
Check Windows Device Manager for sound hardware or audio devices
STEP 1: First check to make sure that your computer has sound hardware installed or that your computer is recognizing the hardware. In Windows 7 choose Start > Control Panel > and in the search box type device manager. Click on Device Manager to open it. (In Windows XP Start > Control Panel > Performance and Maintenance > System > Hardware Tab > Device Manager)
STEP 2: Once Device Manager is open look down the list of devices. If you have a sound card installed you should see it under Sound, Video and Game Controllers. By double-clicking, you can expand the category to view devices.
STEP 3: Once you expand the Sound, Video and Game Controllers category you should see a listing of installed hardware and drivers. In the example below there are several installed devices with drivers that appear to be working. In this case, Realtek High Definition Audio represents the sound hardware for this computer. Yours will look different. If you do not see any audio hardware, you can also check under other devices if that category exists in your Device Manager and look for audio hardware there. If you suspect the computer has no sound hardware installed contact your computer manufacturer’s technical support department. Skip to Step 4 if you have hardware installed.
STEP 4: If you determine that your computer has sound hardware installed but yellow question marks indicate missing drivers either under Sound, Video and Game Controllers or other devices, then you need to fix sound drivers problems.
Windows sounds still not working?
As previously stated, if you have yellow question marks showing up under device manager then you need to fix missing sound drivers.
Did you check to make sure your sounds are not muted, that your speaker volume knob is turned up, and that there is a power (your speakers plugged into a power outlet)?
Did you make sure you have a sound playback device enabled?
Did you check to make sure your speakers are connected to the sound jack, line-out of your computer?