Built-in microphone is not working on toshiba satellite

i have a toshiba satellite l645d-s040 and after reseting my computer the mic does not work. i have tried all the deleting of programs for audio and webcam and even went to the website and downloaded the updated files for audio and video just to see if it was one of them and nothing has worked. i dont want to have to go out and buy a mic since there is already one on the computer please help i am on a time crunch.

thank you