This problem arises when something has gone wrong in the update of iOS 7 and makes the home screen of your iPhone getting stuck with the Apple logo or a white background , making our iPhone not start.
solution:
Press and hold the sleep button to turn off the iPhone.
Open iTunes on your PC and connect the iPhone.
Press the sleep button and home button together for 10 seconds then release the sleep button .
Continue to hold the Home button until iTunes in the following sentence " is detected iPhone in recovery mode , you must restore your iPhone with iTunes to keep using it ."
Select your device in the left column of iTunes , then select Restore . It is very possible that you have to install iOs 7 again.
Should be clear that to restore the computer data is lost but is the only way available to recover the computer. It is likely that in the coming weeks to develop or update tools available to recover the iPhone without restoring .