sound problems

right so i was going through my sound settings, and sudennly i noticed my sound had changed. i went onto iTunes and played a song, and i dont hear voices or bass, only music.. ;/

its the same story on vent, i can hardly hear a person if they talk.... only very slightly in the background..

anyone know what setting i could have changed? :/ or what setting i need to edit..


ps: and no its not my headset, ive tested on other headset and it was the same..