revert Cell value to previous value

[behrensf84]

Hi, Im trying to figure out how to revert the value of a cell to a previous value after it have been changed, when an error occurs. for example, if I have a cell where I only want numbers to be inputted, but someone inputs letters, it would want the value in the cell to revert back to the previous value in the cell rather than have what the user has added. would anyone know how to do this without the use of helper columns?

thank you.

 

[behrensf84]

I have just solved my problem. I can use Application.undo