When I play any DVD (using Windows media player or Realone player) the video works fine but there is no sound, I raised the volume to the max and there was still no sound. I need an audio codec? 
I cant realy say....Widows media play should have all the codecs it needs to play dvd videos....Do you have sound on your computer at all?
That is can you play music, hear the tones and things windows makes?
your speaker is borken !!! or your computer is borken ?!?
i also have the same problem. the speakers are working fine. i play normal avi files and the sound works. but when i play a normal dvd the sound doesn’t work but the video works fine.