First rule with iOS devices, if something doesn't work right restart the device by holding down the power button at the top. Turn off the device when prompted then turn it back on after it has fully shut down (spinning wheel stops). That fixes most problems. If that doesn't work try a hard restar by holding down the power and home buttons until it turns off. You won't lose any data or passwords etc. Most times problems are due to a program crashing and corrupting memory, even of other programs, or a bug in a program that has corrupted memory.