Ctrl and Z: Undo the last action. My favourite key is Ctrl +Z ( when you have feline friends who love your computer this is a must keyboard shortcut to know. 

A must have Cheat Sheet. Did you know that Shortcut Keys can  increase your Productivity by 50%.

Increase productivity with Computer Keyboard Shortcut Keys

Download the free Cheat Sheet for all the most efficient Keyboard Shortcut Keys.