If I insert an audio CD into my computer nothing happens. Nothing at all. According to the Banshee documentation, the CD should "automatically appear within Banshee in your sources list, beneath your Music Library and Video Library sources". It doesn't.
Within Banshee, Edit > Preferences > Extensions > Core > Audio CD Support is turned on.
This problem occurs when using Banshee under a KDE environment. KDE shows the CD as a loaded device, and one can select 'Open Banshee', but if Banshee is already open, it does not load the CD automatically.
One has to close Banshee and restart it for the program to recognize the CD.
If "nothing happens", then your CD drive is most likely no longer working (possibly the laser burned out). Replace the drive and you'll be good to go.
Sometimes when a CD drive becomes faulty like this you will be able to open some CDs but not others.