Just a quick one. I'm unable to select the model and somehow I've lost my reference image. I know I'm missing the obvious, but it's stopped me in my tracks. Thanks
If I'm looking at it right, I believe you might have switched off overlays - I think the hot key is shift + alt + z which I often press by mistake. Hold Z to bring up the pie menu and see if overlays have been switched off. Otherwise I can see the icon isn't on at the top of your viewport (it's the two circles to the left of the viewport shading icons)! I haven't done this course so I'm not too sure about the ref image, but you may have disabled it from the viewport? Click the drop down in the outliner and have a look. I'm on my mobile at the moment so I can't add screenshots. But hopefully someone else night be some to jump in!