These are the instructions to root Samsung Galaxy S2 Plus GT-I9105 (running on android 4.1.2, 4.2.2) using Kingo Root Application on Windows Computer.
Requirements: Your Samsung Galaxy Grand Quattro GT-I8552 should have at least a 20-30 percent battery to perform the rooting process.
(Developer Options is hidden for Android 4.2.2 or above, to unhide Go to Settings > About Phone > Built Number > Tap on it for 5-8 times).
Congratulations! Your Android Device is now Rooted. You can also verify the root status of your device by using the Root Checker App.
[*] No data loss process: Your Android Phone Data like contacts, pictures, videos, music and etc will be not affected with the above method.
[*] Samsung Stock Firmware: If you are looking for the original firmware for your device, then head over to Download Samsung Stock Firmware page.
[*] Samsung USB Driver: If you are looking for the original USB Driver for your device, then head over to Download Samsung USB Driver page.
[*] Credits: Kingoroot is created and distributed by Kingosoft Technology Ltd. So, full credit goes to them for sharing the Application for free.