A customer brought in a Toshiba Satellite Laptop saying that the microphone did not work on Skype. She went on to say that she was not sure when it stopped working but she had the screen replace a few months ago.
The microphone on most laptops is part of the webcam. In theory if the webcam is working then so should the microphone.
I took the surround off the screen and found this:
As you can see there is a piece of rubber with a hole in it that is not square on the microphone below. Therefore the microphone has been muffled by the rubber.
I removed the rubber to show the microphone hole: