I just purchased a new laptop with a built in web-cam & microphone. So far I was unable to activate my microphone. Every-time I record a video through the web-cam, it comes out without any volume ( I could barely hear my voice when I play it back).
Is there some special key that I need to select in the a menu?

What you need to do is increase the Mic gain. If you can hear your voice but its low the Mic is working. Do you have a speaker icon in your task bar?

Yes, I do. But it is already all the way up.
My speakers work just fine when I play other videos. It is just when I record my own video, I could barely hear my voice during the playback.

If you click the speaker icon it should open a panel. In the panel it should say "mixer" it should look like a lot of sliders. In there should be one for "mic" that is where you can adjust gain or you can also go to your sound card controls and adjust it there.

Thanks!