Method One,
Directly from Apple's official website next to iOS 7.1.2 firmware on the computer, and then we
Then connect itunes, press power key 5 seconds and then press HOME10 seconds to enter DFU mode, on itunes press shift not loose select "Restore", and then select the firmware you just started to restore!
Specific steps:
1, turn your iphone off.
2, at the same time press and hold the switch machine keys and home keys.
3, when you see the white Apple logo, please release the Switch machine key, and continue to hold down the home button.
4, open itunes, waiting for its prompt you to restore mode, you can hold down the keyboard shift button, click "Restore", select the appropriate firmware to restore.
Some users in the point of control is not good, leading to the failure to enter the DFU mode, these users can refer to the following method:
1, hold down the top of the Power key 3 seconds;
2, do not release the Power key while holding down the home key for 10 seconds;
3. Release the Power key and continue holding down the home key for 30 seconds until itunes automatically detects a recovery-mode iphone and then loosens it.
Method Two,
You can also download a I4 assistant, according to the above prompts to exit the DFU mode, while the power button down at the same time, when the screen appears white Apple when you let go, you can quit the DFU mode, and also want to talk to the landlord said jailbreak state of the iphone, is not directly upgraded to iOS7, There's no need to try again.
In addition: In addition to our mobile phone using OTA upgrade Apple system does not need to back up the data we use computer to back up the computer will need to back up the data oh, because the use of computer recovery system may cause all the loss of mobile phone data oh.