I had ( have? ) 20 albums stored in the Media Library accessed by clicking on All Music /Artist.
The Artist folder no longer opens. The small + sign will not expand ...dissappears in fact. I have tried other opening options but still end up with a blank or empty screen which used to list the albums with titles and tracks. Where has it gone. I am sure I did not hit anything that said delete all. One day it was there next ...gone. I cannot fathom either where abouts on hard drive it is or was actually stored.
try to do a system retore and go back to the point where you weren't having issues with it. Iron Sharpens Iron.