Why won't my computer play sound suddenly?

I used to have sound on my computer but I just tried to listen to a song from my library and no sound. Then I tried the sound on a game that is preprogrammed into my computer and still no sound. I checked the speakers and they are on and the sound is up loud enough to hear something.

Check to see if you might have hit the mute button by mistake.

First go to start then control panel then look for sounds and media click on audio to see if you have installed it correctly on your computer. Also look in system in control panel click on hardware then device manager to see if the drivers are installed, if you see a yellow question mark, then you need to reinstall the drivers for your sound card. Also check out this website call Syschat it is a tech site http://www.syschat.com.