nosoundman

i have a sony mini disc deck mds je 470, the discs are playing, the deck reads all information, display running, etc etc, but there is no sound, ??.. my discs were recorded in mdlp2 and mdlp4, it is an mdlp player recorder, i have tried my discs on other mdlp players and they are the same, still no sound, ??, i am very distraught over this because i cannot play any of my recordings now, ??, and i cant play them on any other player either, ??, i dont know what happened to the sound, i dont know what to do, ??, what can i do, ??, thanks all, london, england,