I'm sorry. I was referring to the building block templates, one of which is empty, building blocks.dotx. The other, built-in building blocks.dotx, is non-empty and this is the one that contains the gallery content, all the headers, footers, and page number formats.

However, after closing Word and then opening a new blank document, what was displayed in Word after opening built-in bb.dotx is no longer available.

I have also deleted the normal.dotm template with no results other than its regeneration upon opening Word again. And I have opened normal.dotm as you suggest but didn't find anything.