Try restarting iPhone. To turn it off, press and hold the Sleep/Wake button until the red slider appears. Slide your finger across the slider to turn off iPhone. To turn iPhone on, press and hold the Sleep/Wake button until the Apple logo appears.
Does iPhone appear frozen or stuck? Try pressing and holding the Home button for at least 6 seconds to close a frozen application. Then try restarting iPhone following the steps outlined above.
clipped from: www.apple.com 
