The first thing to check is to look at Preferences → Manage Footprint Libraries…
As long as the files you looked at in notepad are still ok, you should be able to add them back using the preferences dialog.
I assumed that a while in:
Was max few minutes 
Thanks for the note, Steve. I have checked that repeatedly. I’ve deleted and recreated that Preferences–>Manage Footprint Libraries many times. The result is that the manager utility seems happy. It shows my library in the list. It shows the correct path to the _.pretty directory. But when I open the Footprint Editor, it also shows my custom library name but with no contents (ie., no footprint models displayed by KiCad, thus inaccessible inside KiCad). Let me say again that the footprint models (*.kicad_mod files) are absolutely there when I look using Windows File Explorer.
I did the footprints upgrade work on Saturday afternoon. Things seemed OK afterwards. When I returned to use KiCad v9 again on Sunday, the footprint models failed to appear and have not been accessible in KiCad 9 since then. I will gladly try any suggestion that others may give.
I remember someone here after moving V7 → V8 had the problems like you and (if remember well) at the end he found that with file manager he was looking into different directory than KiCad (minor difference in the path name).
What is the feature in V9 that you must have?
I have never moved to new version until it was X.0.3 or at least X.0.2 just to skip most buggy versions.
I am not working with KiCad since few months and not plan in next 2…3 months.
Are you talking about 3D models?
Have you checked that your paths in “Configure Paths…” are correct?
Can you share some screenshots of your library configuration?
I wish it were so simple.
No. Not 3D models. I’m trying to fix a problem accessing custom (my own) footprint models. The Footprint Library definition is correct (checked and rechecked many times) but KiCad’s Footprint Editor sees only the directory but no footprint models within that directory.
Are you adding your custom library as Global or a Project-specific?
I recommend using Help → Report Bug to report a bug with your library attached.
Just call them footprints, calling them footprint models risks people confusing them with 3D models.
3 screenshots: File Explorer shows the kicad_mod files in the directory (at top of image) … the Preferences screenshot shows the path to my footprints library … then the Footprints Editor shows the library name but with no contents
Can you try moving it to a local drive instead of using Dropbox?
These network drives have issues with KiCad sometimes.
KiCad 9.0 has now corrupted my .pcb file. Opening __.kicad_pcb shows no footprints and totally garbled mess of random traces (all on the backside of the board where I had very, very few traces before). Even the auto-generated KiCad backup PCBs are showing the same garbled mess, so I suppose it must be the PCB Editor program that’s ruining everything. I can’t spend any more time trying to troubleshoot KiCad 9. I will rip it off of both of my computers tonight and go back to using KiCad 8. It’s clear (to me anyway) that KiCad 9 is catastrophically broken.
If you’ve opened your project in 9.0, then in 8.0, older than 8.0.9, it will disable all objects in the Appearance panel (known bug).
You can enable them back, or delete the .kicad_prl file.
Thank you very much for telling me about that bug. That was indeed the problem. Maybe I’ll be able to continue with KiCad 9 … if I can manage to workaround the custom footprints problem.
Report back after you’ve moved the files to a local drive.
Hi dsa-T. I have the same problem but am not sure what you are showing in the screen capture above. How do you enable them back exactly?
