1. Make sure iTunes is installed on your computer, and then start iTunes on your computer.

2. Now connect the iphone4s to the computer, and then press and hold (iphone4s) power (on/off) and Home (bottom round button) 10 second. When your iPhone goes black, release the power button and hold down the Home button until iTunes finds the iPhone (at this time, there will be a prompt in the lower right corner of the computer to find new hardware).

3. After the computer discovers new hardware, "iTunes" will detect the iPhone in recovery mode until iTunes restores the iPhone. At this point, click Finish in the upper right corner, and iTunes will automatically install and restore the previous firmware version.

4. Wait for a picture of the data cable connection to appear on your iphone4s screen, and at the same time, you will see iTunes prompt that the firmware recovery has been completed, so that your mobile phone can enter the mobile phone without entering a password!