Although Ctrl + Z will undo most all commands before you save a file, if you accidentally undo too much you can always use Ctrl+Y to redo the undos in reverse order.
Ctrl+C is a keyboard shortcut for 'Copy'. Ctrl+V is the shortcut for 'Paste'. Ctrl+X does 'Cut', and Ctrl+Z does 'Undo'. Alt+Tab switches between windows.
There are many different ways to Undo in Photoshop. Ctrl + Z is keyboard shortcut for Undo last operation, Ctrl + Alt + Z is Undo keyboard shortcut. You can Undo and from Edit > Undo or from HISTORY panel (Window > History).
Ctrl + C
The keyboard shortcut for reversing an undo action is typically Ctrl + Shift + Z on Windows or Command + Shift + Z on macOS. This allows you to redo the last action that was undone. In some applications, it may simply be labeled as "Redo" in the Edit menu.
F8
Press the windows key.
Ctrl + V
Windows Key + Tab
crtl-c
Windows key or Ctrl + Esc
Shift - F10
ALT+TAB