Once they "hide" it, it no longer shows in File menu > Open Previous and it no longer shows in Recently Opened Files in the No Company Open screen. So, that isn't helping.
"and I don't know where on my desktop computer it is to retrieve it"
The typical folder is Public Documents, look for one for Intuit, then QB, then Company files. Or, use Windows explorer to find;
And look at the Folders and filenames.
All of this is Windows, not QB. Once you know where it is, you will use the big button, bottom center of No Company Open, to Browse to that .qbw company file. Once you use this to access it, it populates the Most Recently Opened list, again.