Are you familiar with the old saying "Breathe and reboot?" Sometimes you just need to turn something off, power down or unplug in order to start again. This is true of iPhones which - like any other technical device - can sometimes freeze. The first thing to try is to press the "Sleep/Wake" button on the top of your phone. If this doesn't do anything, don't fret - it's just time to breathe and reboot.
Press and hold down the Sleep/Wake button at the same time you press the Home button on the front of your screen. Your phone will automatically shut down or will prompt you to "Swipe to Power Off" causing a "hard reset" to occur. The Big Freeze will be over after your phone has completely turned off and restarted.
Image courtesy of iStockphoto.