On p.17 of the manual it says "If you couldn’t find the microphone (USB controller …)from the Device list, close the S/W and try again. All I can ever get under Recording is "Microphone (Realtek High Def or Microsoft Sound Mapper)
Our manual does not have page numbers, so I don’t know what instructions you are referring to. (This is the current online version of the Audacity manual: http://manual.audacityteam.org/o/)
In order for Audacity to be able to “see” an audio device, it must be recognised and enabled in Windows. Check that your USB device is enabled in the [u]Windows Sound Control Panel[/u].