I once jailbroke my iPhone 6, but then i unjailbroke it again, but the cydia app is still there. I can't open the app, it opens with a white screen and then quickly closes again. I tried deleting everything and rebooting, but the app is still there when i open the phone afterwards. I assume that the app is in the back up, but i don't want to loose everything on my iPhone. What to do?