To All Who Have Helped:
Many thanks!
As a last ditch effort, before replacing the SD card with a new one, I put the card in an adapter and copied the files on it to a directory on my computer for safe keeping. I opened a command prompt and ran CHKDSK (without the fix parameter). I ejected the card, put it back in my ISY994i and plugged it in.
The Iox Launcher immediately loaded the LAN console! My password wouldn't work, so I tried admin. It came right up, programs, scenes, zwave, variables, EVERYTHING.
First thing I did was a backup. I closed the console, restarted it in LAN mode, and it all works.
After all that, I have no idea why, but thanks to all who have helped!