You can undo or redo actions and save yourself some retyping.
To undo an action:
Press Ctrl+Z (Alt+Backspace) until you've fixed your mistake. If you prefer your mouse, click Undo in the Quick Access Toolbar, in the upper-left corner of the Window.
You can't undo some actions, such as clicking commands on the File menu or saving a file.
To redo an action:
To redo something you've undone, press Ctrl+Y or F4. Or click Redo on the Quick Access toolbar.