Mic not working...... hardware or driver??

Hi,
i am using a toshiba satellite L300 and i just changed my OS to windows 7...... now this is where the problem began, ever since i changed the OS from vista to 7, the mic on the laptop has not been working, at first i thought it was a problem with the piece itself so i tried using an external mic rather than the inbuilt one and that didnt work either. When i tried recording myself and playing the recording, it sounded completely distorted, this was the same when i tried recording without the mic as well.......... what is the problem and how can i solve it????