When your iPhone/iPad/iPod screen is black totally, the iOS device is probably in DFU mode. Now you can update firmare, downgrade firmware, or rebooting your jailbroken device. While after that, all the device settings will be changed and contents will be lost.
But if you are careless to enter iOS device DFU mode, how should you do? Believe that you don’t want anything lost or deleted on device. So how to restore iOS device which is in DFU mode?
Step 1: Confirm something you have done before restoring.
1. Verify that the iTunes on computer is the latest version.
2. Back up your iOS device with iTunes or iCloud.
3. Sync device content to your computer with iTunes.
Step 2: Restore your iOS device.
1. Connect your device iPhone/iPad/iPod to your computer.
2. Select your iPhone, iPad, or iPod touch when it appears in iTunes. Select the Summary tab.
3. Click Restore iPhone/iPad/iPod button.
4. After a restore, the iOS device restarts. You should then see "Slide to set up" in iPhone/iPad/iPod screen. Follow the steps in iOS Assistant.
5. After it starts successfully, choose to set it as a new device in iTunes or if needed, restore your device from a previous backup.
Password Recovery Software