No sound coming from files, netflix or other multi media

So, I tried to watch a  movie tonight through my WD Live Plus.  No sound would come through at all, avi file.  After checking the receiver and changing over to cable tv, sound worked fine.  Upon going back into media player and trying again, no sound.  I decided to try netflix thinking it was just a bad audio file for the movie, but again, no sound.  I checked HDMI cable, which is fine.  As of 3 days ago, the system I am set up with worked perfectly for any and all files I play.  I can’t figure out what is happening.  Does anyone have any suggestions?

How is your Plus hooked up?

Do you have the AUDIO MODE set correctly for your situation (Stereo or HDMI or Optical)