TBP fails to launch

When I tried to launch TBP from the PortableApps menu, the menu
disappeared (expected) but nothing else happened. (Not expected since
I usually see the splash screen within seconds of launch.) I checked
with Windows Task Manager to see if anything launched anyway, but it
doesn’t show up on the list of active processes either.

After drilling down to the folder containing the app, I doubleclicked
the .exe file and got this error message:

"The version of this file is not compatible with the version
of Windows you’re running. Check your computer’s system
information to see whether you need an x86 (32-bit) or x64
(64-bit) version of the program, and then contact the
software publisher."

It worked fine when I used it as recently as just two days ago,
typically as it has done across its many versions and updates over the
last five or six years since I first started using it.

What should I do next to fix this?