I've been using Skype with my working mic for weeks and never had an issue.
Today, I tried to talk to my friends but they can't hear me. However when I play a song they hear it.
I didn't update anything or change any settings. Tried restarting the PC but that didn't work.
Checked speech recognition in Windows 7 and when my friends talked on Skype: the volume meter went up, but when I talked it stayed on zero.
So the microphone is probably working but don't know what's really happening?