Q: In app purchase failure

By 'won't go through' you mean ... ? If you are getting an error message then what does it say ?

If you are getting a message to contact iTunes Support then you can do so via this link and ask them why the message is appearing (we are fellow users, we won't know why) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then Purchases, Billing & Redemption

If it's a different problem ... ?

I'm not even getting an error message. Just the proccessing circle and then nothing. It is only happening with one app right now though. I did make a purchase on it this morning for that app, which is what makes it all the weirder for it not to be working now.

Have you tried closing that app via your device's multitasking bar and seeing if it works when you re-open it ?

iOS 7 : double-click the home button to open the taskbar, and then swipe or drag the app's screen from there up and off the top of the screen to close it, and click the home button to close the taskbar.

iOS 6 and below : from the home screen (i.e. not with that app 'open' on-screen) double-click the home button to bring up the taskbar, then press and hold any of the apps on the taskbar for a couple of seconds or so until they start shaking, then press the '-' in the top left of the app to close it, and touch any part of the screen above the taskbar so as to stop the shaking and close the taskbar.

If that doesn't fix it then you could try a soft-reset : press and hold both the sleep and home buttons for about 10 to 15 seconds (ignore the red slider), after which the Apple logo should appear - you won't lose any content, it's the equivalent of a reboot.

Yup that did it