I think previously I had looked at resetting the Utility through the app (rather than via the button, which I cannot get to anyway) but was not sure what would be reset. I don't want to re-setup my wi-fi, if I can avoid it.
I had posted a reply here earlier, and it said my reply would be checked by an administrator, but it's been hours, so I assume my reply got lost somehow. I doubt it would have been refused. If it was, I should be advised. Besides, my previous replies went through right away, no approval required, presumably.
In any case, see this website, where it tells you how to get wi-fi on a Mac without a router:
How to Use Your Mac as a Wireless Router | Macinstruct
Would this work? Let me know your thoughts on this procedure.