undo button stopped working in windows live mail

I use Windows Live Mail for all my emails. My operating system is Windows 7. The undo function stopped working a few weeks ago and I am unable to get it going again. I would also like to add a redo button. I have searched forums but have been unable to find a solution to either of these. Contol+z and Control+y are sometimes advised, but they don't work. Non-tech answer please, or I won't know what you are talking about!