Well, I did a major screw up... perhaps. I maintain a library of about 32,000 font files on a portable drive. Using "Font Manager," I attempted to get (just) a listing of all of those fonts, as both Font Matrix and the old FontyPython were not cutting it. Instead, it appears that I "installed" all of those fonts. Took Font Manager twenty minutes to reload.
I would like to know where to look to remove any cache of information that Font Manager is using so it will start from scratch. At a guess (only), the fonts themselves were not physically moved to the main drive, but perhaps that needs to be checked as well. All help would be appreciated; though I have worked on computers for 30+ years, I've only been fulltime on Linux (LM17-64) for about a month (and relieved to do so), so please be explicit.
In all of those years (most in Windows, the last 5+ in OSX), I used such font managers as Fusion, Font Expert, etc. I know that level of app does not exist in the Linux world, but I am open to suggestions for anything that is more up to date than FontyPython and (much) better at comparative display than Font Matrix (really disliked that one).