Ken, thank you. I went to the TuringTest2 article and I quote: "With iTunes 12.2 or later it may pay to turn off iCloud Music Library and Apple Music before attempting to restore an older copy of your database as shown below. These options can be found under Edit > Preferences > General (Windows) or iTunes > Preferences > General (Mac OS X)."
I went to iTunes preferences (with iTunes open) and found that I can't turn off the icloud Music Library. I don't use Apple Music.
I have a thumb drive with some of the music in a file. I changed the library location to "/Users/kmk/Desktop/iTunes Music." "iTunes Music" is the name of the thumb drive music file. That didn't work.
So I reverted to my ancient file-moving technique. I dragged the albums one-by-one to the iMusic application. That worked. Unfortunately I don't have all my CDs on the thub drive. I think I have the CDs.
(I even stumbled onto previous iTunes libraries but they were all the same, identical to what appeared in iTunes.)
And I have explored iTunes and I have received wonderful assistance from the community. I'm sure I will have more questions in the future.
Thank you or your interest.