Movies Lost Dialogues Sound - Background Music Fine

All this happened suddenly, I was playing Counter strike and I could hear the back grounds but the dialogues and gunshots could not be heard. After that when I tried some movies, All the dialogues had been gone. I could hear the background music and background sounds but the midtones had been gone.

I tried many media players and different files but all had same results. The funny thing is The audio files are working all right only the video files have the problem. I tried restarting, Tried diff video files and diff players including VLC, Windows media player etc.