Mistakes arise and can be reversed by using the Undo command.  To use this function, pull down the edit menu and click on undo typing.  This will allow you to undo the last command.  While the Undo command is common to all Microsoft Office applications, Access enables the undo of only the most recent command.  The fastest way to access the undo command is to click the shortcut undo button also located on the Microsoft Access toolbar.