Did you look at Building Blocks & AutoText?

Yes; as far as I understood it, it didn't deal with the situation when the building blocks organizer is completely empty. Yet if you open built-in building blocks.dotx directly, all the building blocks are displayable.

Which Built-In Building Blocks.dotx file are you opening directly? You may have more than one on your system.

Are you opening the one in a subfolder of your program files folder, or the one that is in a subfolder of your AppData folder?

On my computer I have one at
C:\Program Files (x86)\Microsoft Office\Office14\Document Parts\1033\14
That is not the one that Word uses. Leave it alone!

There is a separate one at:
C:\Users\username\AppData\Roaming\Microsoft\Document Building Blocks\1033\14
This is a hidden system folder and you have to override Windows defaults to see it.
That is the file that should be renamed.

The latter is the one I have been dealing with. I haven't touched the other.

Have you tried renaming this file?

Yes, I have renamed the file, which had no effect.

And I have looked at live content\...\1033. I found the folder empty. The building blocks.dotx file that you indicate should be there isn't. I was surprised but did not know where to go from there and, to be truthful, did not know what to make of this.