Vista - Help! Microphone on headset working on XP but not my Vista.

Microphone on headset working on XP but not my Vista. It was working fine but about a month ago it stopped working. It's driving me completely nuts, I tried everything I could but to no avail. Im using Realtek HD and my headset is Creative HEADSET HS-450, processor AMD Phenom# 8650 X3 Triple-Core and I have Vista Home premium 32bit. Any experts of the kind? I really need help and don't know what to do or where to turn. /starshine

The microphone is detected, its set as the standard unit and I tried de-activating detection of front units. Its not muted and I updated for the latest Realtek. I tried to plug the microphone jack into all of them and noone seem to work. The wierdest thing is it was working just fine and then one day it just stopped seemingly from no action of my own!