MX-19.3_KDE_x64 patito feo November 11 20
Linux neon-Asus-ROG 5.8.0-3-amd64 #1 SMP Debian 5.8.14-1~mx19+2 (2020-10-25) x86_64 GNU/Linux

I've lost all of my applications in the Application Menu. Is there some way to restore the default Menu?
OR
I've probably got a backup of whatever file(s) were damaged but I don't know what I'm looking for.

This seems to have been triggered by running "KMyMoney-5.1.1-a1a0fcb-x86_64.AppImage" downloaded from here:
https://binary-factory.kde.org/job/KMyMoney_Stable_Appimage_Build/

Any help would be much appreciated.

This is really weird. After losing all my menu items I tried re-booting, which did not help.
I tried a Restore with Back-In-Time that I'm not familiar with. I think I restored all of the hidden files in the Home folder.
That made no difference on a LogOut, nor a reboot after that.
I left the computer on and idling for a few hours while doing life, and low and behold the Menu had re-populated itself.
Now when I do a re-Boot, all the Menu entries are there, My Menu Favourites are there AND the Default Menu Favourites show up.
Deleting the Default Menu Favourites gives me my preferred settings UNTIL I reboot and then the Default Favourites again show up along with my own.
Definitely workable and saving me from having to add a new user and re-configuring everything again.
"The Ghost In The Machine"? In any case I've marked this solved.