Thanks for your advice. I uninstalled EVERYTHING as you advised, and reinstalled an older version.
This eventually worked.
Unfortunately I then got cocky and tried to connect my Iphone XS to my now fully functioning itunes and received the message - ITunes could not connect to this iPhone. An unknown error occurred (0xE800000A).
I then tried to update to the latest version again hoping this would solve that issue but I'm now having the original problem. I will start from scratch again tomorrow.
A weird side note - I contacted Apple Support. When they screen shared with me, all of the missing information appeared on itunes. When they disconnected from my laptop, all of the information disappeared again. Why is upgrading never a simple process????