Do you know how to set up time and weather on the lock screen? If you do, set it up (again).
Unless you've updated to Pie. I noticed that a lot of widgets get put on the screen, but they don't show (I'm not using the lock screen for anything but unlocking the phone.) I have a nice analog clock that sits on a home screen page - I can long-press the blank spot and I get the Resize, Delete, etc., menu, but there's no clock. It worked on Oreo, it doesn't in Pie. Something Google is going to have to figure out. (Something all the beta testers missed.) Then, if you updated to Pie, it's probably there, just invisible.