I'm trying to play american dad, and it does not have any sound. But I have another dvd about music (videos) and it does have sound.

Why is the american dad dvd silent?

try to provide some more info, like:

- what player(s) did you try? (check VLC portable - http://portableapps.com/apps/music_video/vlc_portable , at least as 2nd opinion...)
- what mediainspectors did you try? (mediainfo and such)

Power DVD works, but WMP doesn't. What's up with that? Two other DVDs work with WMP.

I tried WMP first.

American Dad DVDs don't have region encoding listed, I guess it's 0. two are single and one double layered. 5.1 sorround but works with stereo.

It's NTSC and it's full frame 1.33:1.

It is copy protected, but I don't know if it's a corrupt disk or not.

that would mean you don't have any 3rd party ac3 decoders installed (i wouldnt bother thougt, just use VLC if you don't like powerDVD for some reason...)