I had this trouble for a very, VERY, very long time. I tried pretty much everything suggested to no avail. One day by chance, my hand slipped and slid down the opposite side of the top edge and MIRACULOUSLY the notification bar pulled down. I don't have any idea why this worked but you might try accessing the pull down from a different location on the top of your screen. Perhap include the phrase 'Abracadabra or Shizam!