Why does My Laptop Fail To Recognize Built-in Microphone?

Amazon My laptop is an ASUS model with i5 CPU core. It's got a built in microphone as the spec says. However when I use Skype for some reason it does NOT recognize the built-in microphone. If I use an external microphone then it works. Here's the solution!

Solution
After some tweaking and searching I finally found that the microphone setting is in the following location:

Control Panel -> Sound -> Microphone is "not enabled".
After I set it to "enabled" it works!

If not let me know!