Mouse no longer working in Mojave 10.14.3

I got back my computer from the Apple and they had installed Mojave on it...even when I specifically asked them NOT to put it on there. Now, my mouse cannot click on anything. I cannot click, i cannot drag. The mouse cursor moves, but you cannot click anywhere. I saw this posted in another thread, but it wouldn't let me respond to it. Anyone else having this issue after upgrading (or in my case being involuntarily upgraded to) MacOS Mojave?

Mouse will not click in Mojave?