A colleague of mine had a long going trouble with his Ubuntu10.04. He kept installing/uninstalling drivers as a part of his project. He got stuck up when his mic did not get detected in ubuntu. He tried the mic test in skype, but in vain.
I suggested him the following solution:
1. Goto Sound Preferences
2. In that goto “Input” tab
3. In that you could see “Connector” option. Try each of the options and do the skype. You would succeed in any of the selections!
4. In the same tab there is an option “Choose a device for input”
For that option, i just have one device listed: “Internal Audio Analog Stereo”
If you have any other option, try them too and do the skype test!
The above solution did not work for him. Finally he figured out a solution in youtube.
Have a look: