To undo with the shortcut on Windows, press Control + M + Z at the same time. To use the shortcut on a Mac, press Command + M + Z at the same time. To redo your last undo, use Control + Shift + Y (PC) or Command + Shift + Y (Mac). [1] X Research source

For example, if your last action was converting a cell, you’ll see Undo cell conversion. If the last thing you did was delete a cell, you’ll see Undo delete cell. To redo, click the Edit menu and select Redo.