Can't access iTunes on Mac and iPhone?

Hi, I recently tried to update an App on my iPhone, but after I inserted my password it said "Can't connect to iTunes Store". At the moment I was connected to a Wi-Fi connection, but then I tried to download it with the 3G network included in my phone plan. Same message. I then tried to download a random free app from my MacBook Pro, but it said it the same thing, and to try again later. I signed out of my account on my Phone, but when I try to sign in again it won't work.iTunes on my computer won't even let me sign out. I'm pretty sure it's not a connection problem, but I don't get why I can't access it! I can browse through apps without any problems!
What could the problem be and how can I access my account again?

Well I'm sure it is a connection problem if you haven't paid your bill than do so. Or else reboot your mac just restart your mac and press command-s then type in reboot thanks for reading with your iPhone reset it but don't delete everything