Couldn't download an app and now cannot log into my iTunes account?

I had deleted Instagram a few days ago and I just tried to redownload it, but the icon wouldn't even appear; it just said "waiting" and disappeared. I then turned my phone off and tried it again, but still nothing. I tried downloading a different app and the same thing happened. I then reset it by using the home and lock buttons. It still did not work, so I logged out of my account but it wouldn't allow me to log back in. I keep getting the error message "Cannot connect to iTunes Store." I know that it's not my internet because everything else is working just fine and all of the other apps are working normally. Is anyone able to help me?