I can't remember the fix I used to, well fix this provlem, but it certainly happened to me a few times and is a really frustrating experience. First, I was trying to download an app, just a pretty small app, a few mbs, but it won't download and stay in a state where it says "Waiting" and the icon is blank. After a few minutes the icon disappeared, without any warnings. I figured "Nah wi-fi is just slow" but I checked on safari and other apps thats uses wi-fi and they work fine. The app store loads all the images and pages without a hassle. So I tried logging out if my apple ID and logging in but after logging it it would just stay greyed out, and after a few minutes it would say "Cannot connect to iTunes store". These are the steps I tried to fix this: Restart, rebooth, the set the clock 1 year before and set auto again fix, and reset network settings. Any help is appreciated.