Restoring Selections
Often, while in the middle of working on a tricky selection, you’ll
accidentally deselect it by clicking once too often. You can restore the lost
selection by pressing Shift + Control/Command + D. This will get the
ants marching again. You can also undo (Control/Command + Z) the
action, and even perform multiple undos with Control/Command + Alt/
Option + Z.
By the way, you can hold the Alt/Option key to subtract elements from
the selection at any time, or hold the Shift key to add to the selection.
Pressing a combination of both keys creates a selection intersection.
Important selections that you might need later can be saved by going to
Select → Save Selection.
Restore lost selections.