Im missing tools such as Adaptive Skin, Rigging, Topology, and so on.
How can I bring them back?
Add a zsphere to the canvas.
The ZBrush interface is context sensitive. It changes depending upon your current selections. Since those specific features only apply to ZSpheres, they are not present in the interface when a different type Tool selected.
It’s just like if you select the SimpleBrush – all the menus in the Tool palette disappear because none of them apply to that brush.