The internal microphone on my hp mini 1001TU does not work with sound recorder or skype.
Go to sound settings.
If you are using Unity, then type Sound in Dash.
Under Record Sound from, select Internal Microphone.
It's settings will be shown on the right.
Make sure that Mute is not selected.
Hopefully, your Microphone should work fine now.
To get help, best one on this Alsa sound issue answers.launchpad.net/ubuntu...ce/alsa-driver Steps to get help.
He has details tutorial too.