My laptop's built in microphone is not working?

My laptop's built in microphone works on my sound recorder and it is activated the thing is that whenever I try to chat with somebody on facebook chat and I click yes to let it activate my microphone and webcam my webcam works but they can't hear me. And when I use it on my sound recorder on my computer it can barely hear me. What do I do? I have a windows 7 laptop.