Can't see objects on 3D grid

Hi. I can't see any objects on my 3D grid. For example: the boxy camera model that you can grab and rotate around. I can see images I've placed in front view but can't "click" on those and see handles. What am I missing or failing to turn on?

Thanks

You many have turned off your overlays - look under the View pop-up menu. Make sure all your 3D overlays are turned on as well.