Now, when accessing that drive in the library, all images have the dreaded question mark. Tried several methods to overcome this with no result. Didn't find anything to address the problem online or in help.
To add insult to injury, I'm shuttling between two residences twice a week and getting ready for two weeks abroad, so dealing with sleep deprivation at the same time.
Hope there's an easy solution.
In Folders panel, right click the top level folders and choose Find Missing Folder. Do it when you can think clearly - for now, don't do anything to make the situation worse.