After upgrading to High Sierra, iTunes deleted user and songs
After upgrading to High Sierra, my MacBook Pro deleted the other user [which was created when upgraded to Sierra], as well as all new songs in iTunes. I have borrowed 20 CDs from my uncle, and copied to my iTunes library; converted & saved some music from Youtube - all gone!! Where can I find the deleted user, as well as all songs?
MacBook Pro (15-inch Late 2011), iOS 10.1.1