This option allows you to back off any changes that have been made. The undo 'buffer' is cleared by saving the workbook or running code however, so you should make sure everything is as you want it before taking that option. The undo option is multi-level and will undo many changes. These can be reviewed by clicking on the arrow to the right of the undo toolbar button.

VBA

Nb: This must be the first line in the code as it will not undo actions taken by any VBA code, it will only undo the last action taken in the user interface.

Sub UseUnDo()()
Application.Undo
End Sub