how do i see non-purchased music - it has disappeared on iTunes 12

Hi DrBobL,

I'm sorry to hear you are having these issues with iTunes. I also apologize, I'm a bit unclear on the exact nature of the issue you are describing. If this happened after a recent update, you may find the troubleshooting steps outlined in the following article helpful:

If you don't see your content after updating iTunes - Apple Support

Regards

It has always been very basic to always maintain backup copy of your computer. If the music is gone, then copy it from your backup to your computer.