not allowing me to access camera through snapchat or instagram

help!!! i can't access my camera in either snapchat or instagram. every time i go to settings, it doesn't show the option to allow my camera to be accessed. i've already deleted both apps and redownloaded to allow it through the push notification, but the push notif never showed up. i also checked my privacy settings and nothing there said snapchat or instagram was being blocked from my camera. help please!!!