If you can see walls and slabs in 3D but not the objects then I would look at the renovation filter that is active and/or the renovation settings of your objects.
If you can see nothing in 3D then change to the Internal Engine.
If you can see the 3D now then I would think it is an OpenGL issue.
Try updating you video drivers, or you say there has been some PC maintenance, so you may have to revert to the original drivers if that has been changed in the maintenance.
Barry.
One of the forum moderators.
Versions 6.5 to 27
i7-10700 @ 2.9Ghz, 32GB ram, GeForce RTX 2060 (6GB), Windows 10
Lenovo Thinkpad - i7-1270P 2.20 GHz, 32GB RAM, Nvidia T550, Windows 11