Hi,
This issue is REALLY irritating me. It is soooooo annoying.
Last night, Unity was working fine, I made myself movement scripts, had terrain etc. All was working well. I left my computer on, and this morning, objects started disappearing when you deselect them. Also, when you spawn an object (for example, cube) the object doesn’t really show up. It’s just a square with those locked arrows for movement…
Same with everything else, like Camera. The icon of that camera is just that little grey square. And when I deselect those objects, they just disappear and they can’t reappear. Only way they reappear is if you select them in the Hierarchy.
Please help me! I need to get my self-project done… 
3 Answers
3lighting enabled with no light source?
make sure in the top left its
scene Game (picture of sun)
textured RGB
the picture of the sun should not be depressed, that turns on lighting, which is bad if you have no light.
if textured says something else like wireframe or RGB says something like alpha your in the wrong view. click on the words and change them
Did you try restarting Unity and/or rebooting your machine?
Genetix i did what you said. Its on Textures and RGB and i selected the sun. Still same issue
And DaveA, I already reinstalled unity, restarted my pc, and restarted unity.