I have installed LibreOffice v5.3.6 from a downloaded executable file, on more than one occasion, onto a computer running Windows 10 Pro, 64-bit. There is still a Libroffice folder in Program Files. It is completely empty.
I’ve installed the software several times, and it’s never there when I go to use it.
Did you look into correct location? it could be that you are installing a 32-bit version on a 64-bit system, and so it goes to Program Files (x86), not to Program Files (the empty one there could be a remnant of a former installation of different bitness LO).
Does your installation succeeds at all? any error messages?
Can you use LibreOffice regardless of empty directory? Do you have shortcuts on desktop/main menu? Where do they point to?
You may have a program installed¹ that reverts changes to the disk each time the computer is restarted.
¹ (Digital Guardian, Faronics Deep Freeze)
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