Answer - This problem comes up while updating or
iphone crashed in between.Follow the
following steps:
Enter the phone on the DFU mode *******************
After the phone gets on to the DFU mode then try to
connect the phone to the computer and then open up itunes and try to run a
recovery option . http://support.apple.com/kb/HT1808
Note
- if you do this step then all your store data on your phone will be lost.
