Lost Utility Desktop

I updated my iMac on February 6, 2019, to Mojave. I still had a lot of trouble accessing the the internet, but Justin at Apple Care was able to help me fix that.

Now my problem is this: the desktop that displays the calculator, world clock, or whatever widgets are put on it, is GONE! I can two-finger swipe across - both right and left - to access the other desktops, but the one with the utilities I had customized has disappeared. Any suggestions?