What can i do about guitar amp headphone problem?

I have had my line 6 spider IV 15 guitar amp for about a month. It has worked perfect until today when I plugged the headphones into the jack (as i have done many times before without problems). I plugged in the headphones and no sound came out when i played. If i take the headphones out just a little bit the sound comes through, but all distorted. So if I put the headphones in all the way i get nothing. Does anyone know what is wrong or how to fix this?