Alienware 17 Windows 7 - Webcam and microphone not working

Hi everyone !

Everything is in the title : I own a 2 years old, windows 7 operated alienware 17 and I discovered yesterday that the integrated webcam and microphone are not working.

The system simply behave like they don't exist, I can't find them in the device manager and when trying to skype call someone for exemple, skype tells me there is no webcam detected.

I have no idea how the problem occurred since I haven't tried to use webcam/microphone in a while and hence have no idea how come it suddenly doesn't work.

Please help ! 

Thanks in advance