Okay, someone's got to ask the stoopid question (SQ): Did you check the volume? It's a separate setting from the regular, no-headphones-plugged-in volume. Oh, and SQ#2: Did you check a different set of headphones to see if it's the headphones?
Huh. Seems that's all I know to ask. Hopefully, someone else will be along with the not so stoopid help. Good luck.
Marilyn