check to make sure your speakers are plugged in where they should be and that they are on, then check the volume level or if it's muted or not (yes yes i know it's simple but you'll be surprised how many people forget this step.)

If everything is in working order, try downloading an alternative media player. For example, WinAmp. It looks like you are getting some type of error in Windows Media Player so it could be corrupt altogether. Try a different player.

If that doesn't work you'll have to troubleshoot your sound card to see what's up. PM me and i'll try to help...