How to fix a built in microphone on a Dell Inspirion N5030 Laptop?

My Dell Inspirion N5030 laptop is only three months old and I went to record a song on a karaoke site and it said my microphone was missing; so then I went to hardware and sound - sound - manage audio devices, and it says I don't have a microphone. I don't understand how it could just disappear. I can hear the echo of it when my sound is on. Can anyone help me?How to fix a built in microphone on a Dell Inspirion N5030 Laptop?reinstall the driver for the mic