Entering and Editing Data
Excel's Undo feature lets you “take back” as many as 16 of your most recent actions. Just click the Undo button on the Standard toolbar (or press Ctrl+Z) over and over to undo things you've done, one by one. Or click the down arrow to the right of the Undo button and select several actions to undo all at once.
The Redo feature lets you redo the same 16 most recent actions.