Audio capturing not working

[Phil]

Thank you for reading this.

I have a scheduled Skype session and for some unknown reason audio 
capturing is not working. It has worked without any problems in the past.

Kmixer reports "Nothing is capturing audio" and under System Settings -> 
Audio and Video Settings, the "built-in Audio Analog Stereo" icon is 
greyed out.

As I say, this has worked flawlessly in the recent past.

Any suggestions on how to get this working again will be greatly 
appreciated.

-- 
Regards,
Phil