I understand your microphone is not working in Skype.
What is the product number?
NOTE: Do NOT provide the serial number.
Does it work if you use Windows Sound Recorder to test the microphone as outlined towards the bottom of the following document?
http://h10025.www1.hp.com/ewfrf/wc/document?cc=us&lc=en&dlc=en&docname=c03421813