In a couple of decades of using LibreOffice, since when it split off from Open office, I have never had offline help work, ever. I get obtuse answers on how it should/could/might work but have never had success in getting it to work.
I am in no way a ‘power user’ but that seems to be the point of help files, to help those like me, as well as those that use it all the time, every day.
With that straightened out, I’m running the most current version, LibreOffice_7.4.2_Win_x64, that is supposed to have built in help and an installation program that should make help work but always get;
Your file couldn’t be accessed
It may have been moved, edited, or deleted.
ERR_FILE_NOT_FOUND
Just to be 100% clear, it was not touched in any way, I just reloaded the file and I have NOT moved, edited, or deleted any files.