You can't format the iPhone from your computer. If you want to completely erase the memory and restore it to the factory default settings, go to Settings->General->Reset->Erase All Content and Settings. It will take between 1 and 2 hours but when it's done, you will have a completely erased iPhone.
Keep trying the dfu mode it is tricky and you have to get it just right. Remember hold the home for 5 seconds then power and home for 10 seconds then releas power and continue to hold home for 30 seconds until your of recognizes it (hopefully)
I installed a game into my iPhone direct from internet. after finish the installation th iPhone hanging and restart. till now the Apple logo when you see it in restarting is shown only and i could not booting to it . it is restarting by it self every 10 mint.
So guys I need your support to help how can I resolve my problem with keeping my data as it is.