The keyboard shortcut for undo varies depending on the application and operating system being used. Here are some common keyboard shortcuts for undo:

• Windows: Press Ctrl + Z to undo an action. To redo an action, press Ctrl + Y or Ctrl + Shift + Z .
• Mac: Press Command + Z to undo an action. To redo an action, press Command + Shift + Z .

Its important to note that not all applications support the redo action, and some actions cannot be undone.