Microphone being a jerk.

Okay, so I have Windows Vista and I recently wiped my computer to make it go faster, and I reinstalled all the drivers I was supposed to.
But for some reason, my internal microphone isn't working. And I tried setting up a line-in microphone but that wasn't working either. I downloaded the sigmatel driver from the dell website because that was supposed to help, but it didn't.
The only thing I used my mic for is skype, and it was working perfectly before I wiped my computer, now it's not working. I've tried going to Control Panel and Device Manager and on Skype itself, but I've tried everything I can think of and nothing works.
Help?