My old, little used laptop has just installed a series of Win10 updates, now fully up to date, since when my keyboard has had problem generating a question mark.
Question mark is on the shifted forward slash key - ////. Either of the shift keys work fine with all the other keys to produce the caps etc., but pressing the left shift key + ? may require as many as 10 presses to produce a question mark. Right shift key + ? works every time.