I just bought a cheap lapel mic to record the voiceover for the occasional gaming video I do. Tested the mic on my phone, it sounds great. Windows recognizes there's a mic in the front 3.5mm jack. But nothing picks up the sound from it. I've tried Audacity, Windows Voice Recorder, Radeon ReLive, and the Windows speech recognition setup program. None of them get any input from the mic. I'd say there's a problem with the jack, but Windows does recognize there's a microphone there. So it has to be connected and detectable.

I figured this is probably the geekiest forum I'm part of. Hopefully somebody has an idea.

I use Linux, not Widows so can't help directly. A couple of things to try, if you didn't already.

In Audacity, set recording to Line In.
In whatever Audio configuration utility you have, be sure to set Microphone volume all the way up and not muted.

My wife solved it. Turned out to be a hardware issue, not software. I didn't realize there were differences between 3.5mm jacks. The plug on the mic cord has four channels but the jack on the computer has two. The adaptor that came with the mic, which I thought was just a different size, made everything peachy. The 4-channel plug works perfectly in my phone. So that will be handy; I can leave the adaptor and extension cord plugged into the PC and take the mic with me when I want to record actual video with my phone.