Stereo mixer with a Microphone Headset?

[Sean]

I have windows 7, and on my recording devices section, It says "sound mixer is currently unavailable", I heard that you need a microphone to use sound mixer, I don't have a regular microphone, but I have this microphone headset. Will that work? If so, how can I make it work?
The Mic is plugged in, yet it still says that Stereo Mixer is currently unavailable...