What is the name of this item and how to get it back? I think I pressed an unintended keyboard shortcut and this cursor thing



in 3D view disappeared. What is the name of it and how to get it back?

I am already in object mode, not in edit mode.

Edit

From the comment, it seems that it is called "manipulator". However, pressing Ctrl+Space does not show it.
It looks like I have disabled all manipulators like this:



in which case pressing Ctrl+Space does not have an effect.

Turning on at least one of them like this:



brings the manipulator back.

Hovering over the item does not show a keyboard shortcut, so it must have been a mis-Shift-click instead of an unintended keyboard shortcut.