daz

I can any one help i got my son a sony n510 for xmas. I was playing fine he tryed to record thruogh the optical cable from the dvd player on my stereo which seemed to be going ok . But when it ad finished recording it wont play back on his md the disk spins tells you the amount on disk but no sound. i would be grtfull for any advice as he says hes not olterd the menu at all. thanks daz