Dvd plays movies but no sound! ARRRRGGHHH!

I bought a new cd/dvd player, installed it and spent the past 3 days trying to get sound. It doesnt need the cable. Today i bought a new sound card and that didnt fix it. Nero software came with the player and on both my players, cds work, dvds play but no sound just from dvd’s. Ive installed several coders. Finally I found AVS software that works but i really need to find out why nero,media player and others will not play sound. Is it maybe that AVS isn’t connected to windows and maybe i have a windows file corrupted? Ive tried everything and i’m quite sure all my settings are ok.. I dont need the cable cause i have XP and it works with AVS without the cable. Thanks. i’m so confused.
Barb