Itunes wont open

I would first try shutting down every process in Task Manager (hold down: Ctrl / Alt / Delete keys) that isn't necessary to run your computer. Next, if that didn't make it run properly, try installing iTunes while in safe mode. You'll have to consult your computer's instructions for entering safe mode. If that doesn't fix it, you may have to re-install Windows (I've assumed that you're running Windows).