Hi
i asked many times but no answer no solution now my IPhone back to life after 3 monthes .....
Thanks for great man who help me.

I found this solution so i would like to share it with you.

1) Download the latest version of blackra1n.
2) Plug the phone into your iPhone USB connector, plugged into a Windows machine running iTunes and blackra1n.
3) The phone will show as connected but will NOT charge. THIS IS EXPECTED BEHAVIOR.
4) Keep blackra1n open and keep the phone plugged in, and go do something for 8 to 12 to 16 hours. This is a VERY IMPORTANT STEP.
5) When you come back to your phone/PC, your phone should be at the home screen and charged and you should be good to go.

WHAT IS REALLY HAPPENING:
When the phone gets stuck in the reboot loop, it is unable to charge via the USB connector plugged into the PC because the iPhone doesn't get that far in the boot process before the race condition exhibits. The device gets far enough to mount the root filesystem and to provide filesystem access over USB, however. When you leave it plugged in and walk away, what you're really doing is allowing the iPhone to completely discharge its battery. When it does this, it will power off. Once it has powered off, it will begin charging via the USB cable. Once it has sufficient charge to power on, it will power on. During the power-on process, blackra1n will see the iPhone and will kickstart it.