I have a 20 year old database with tens of thousands of pictures in hundreds if not thousands of folders. Is there a way to search the entire database for orphans.
You could select a drive in the Location panel, right-click on it and turn on 'show child folders' so that thumbnails from all its folders and subfolders will be shown.
Then go to
Edit | Select By | Orphans to select all orphans. Maybe from there you can add them to a new gallery, from which you can examine them and get back to them later.
Repeat this for any other drives that may have orphans.
EDITED TO ADD:
p.s. In the
Options | Preferences | Thumbnails screen, please be sure to have the "Show Orphans" setting ON and "Auto Remove Orphans" OFF. I think those are the default values, but just in case...