No sound either internal speakers or headphones. Anyone help?

i have no sound at the startup or on any application that sound should come from. my itunes songs would not play for that fact even. tried the nvram?pram thing, tried the headphones solution, tried the paperclip thing. nothing works. updated my software as well, still no success. volume slider is grey, and volume adjuster on keys F11 & 12 are forbidden. no output or input devices found even when i plug headphones in. PLEASE HELP