michaeljhubbard wrote: did try to access the photos library from the Pictures folder of my home folder, but it is empty.
That's the right place. You didn't say--are you using iCloud Photos to synchronize Libraries? If you are, then what do you see at iCloud.com?
It's possible that the original Library was accidentally moved to another folder. You can do a Finder search to hunt for it. A Photos Library has a suffix of ".photoslibrary" with the "." leading it, so you can put that in the search field in Finder like this:

I have several Libraries, and you can see the path to the selected one at the bottom of the search window.
MacOS updates don't, on their own, erase Photos Libraries, but if the Library was in an unusual place, Photos might lose track. Speaking of unusual places, have you looked in iCloud Drive (or Mobile Documents) in the Finder's sidebar?