What do you mean by a "onenote file" ?
I ask because there is no real need for that MRU ...
1. Notebooks should stay open and are never listed in the MRU
2. The only "onenote files" that are listed in the MRU are explicitely
opened sections circumventing the containing notebook, or orphaned
sections. Both methods are in my opinion rather unusual, exotic ways of
using ON.
But if you really want to open a special section directly you should/could
create a desktop shortcut for it.
I just thought I'll have one notebook for organizing notes related to home,
and another for organizing notes related to work (but resides on my home
pc). I thought this would make it easier if some day I want to bring the
work related notes to work and put it on my work pc.
Perhaps this is the wrong way to use note, that I should have only one note
"file", and create different sections for work and home?
But back to the original question. If you accidentally close your notebook
in the onenote app, and the "file" isn't on the MRU list, then how do you
open it back?
I did manage to locate the "file", which is a onenote TOC file inside a
folder containing other onenote related files.