I know this sounds simple but some head sets have switches that mute the mic.
You havnt told us if the audio works in the screwed up head set or not.
Is this head set USB or analog mic in? Are you certain your putting the right mic cable into the right input?
Right click the audio icon on the lower right of your screen and see what its telling you about that mic. Make sure its selected with the check mark. Select it, go to propertys, and see if you can hear yourself when you check "listen to this device".