Gateway dx4840-11e. During video can hear music but not actor voices. What to do?

Do you have the sound set to surrond sound? What it sounds like is that it is trying to play through surrond speakers but you dont have them, which is why you can hear the music and not the actors voices. click with the right mouse button on the speaker in the bottom right of your screen, then click on sounds , now click on the playback tab in the sound window, click on the sound device shown and then click configure, choose stereo and choose two speakers. Continue to the end then try to play the video and see if you can now hear the voices. If you cant then you maybe missing codecs needed to play the audio correctly. Please state if this is a movie you have downloaded or a dvd film on disc etc