I can't get sound output to a Sony MD

Hi all, New to this forum so apologies if this has already been raised. Recently upgraded from xp to win7. Have since updated to latest realtek drive. I can't get sound output to a Sony MD via front jack which used to work before the os upgrade. Even if I plug in a headphone I get no sound other than from the speakers. Speaker sounds are great as before. With the front panel sockets pink (mic) green (headphone) I used to be able to plug into either and realtek would automatically select the right source. Spkr config is stereo, No sound fx or room correction and default format is CD.
Any ideas anyone?

Found the answer within another thread and the information to amend the registry, so thanks to the poster for that.