First of all you need to backup your iPhone and for that our post will guide you.
After taking complete backup of your device, you need some tools that are iOSBoot Genius & iTunes which will be helping you to reset your iPhone.
After downloading these tool in your windows PC install them.
Now take the original USB data cable of your iPhone and connect your iPhone with your computer using it.
Now launch the iOSBoot Genius tool in your windows PC and wait for the tool to detect your iPhone that you connected with your PC using USB cable.
Now you simply need to enter to the recovery mode of your iPhone by clicking on “Enter Recovery Mode” of iOSBoot Genius.
Now a popup from iTunes will appear asking “iPhone is in recovery mode and you must restore it before it can be used with iTunes” then simply click on Ok.
