How do you change É to a question mark?

If you press and hold ctrl, Fn, and shift, it should change back to a ?.

A more common reason that this happens is because your computer decides to change the language on your keyboard by itself when you do not notice. For Windows users, you will probably see a little keyboard icon and an abbreviation of a language. Click the letters to check which keyboard you are using. Click the keyboard to check which language it is in.
If the icons are not shown...
-Click Start > Control Panel > Clock, Language, and Region > Change Keyboards or other input methods > Keyboards & Languages Tab > Change Keyboards > Change it!
If you want the icons to show...
-Right-click the Taskbar(usually at the bottom) > Toolbars > check Language Bar
Hope I helped!