These are the instructions to root Samsung Galaxy S2 SGH-I777 AT&T (running on android 2.3.4) by using vRoot tool on windows computer.
Requirements: Your Samsung Galaxy S2 SGH-I777 AT&T should have at least 20-30 percent battery to perform the rooting process.
Step 1. Download and Install Samsung USB Driver on your computer. If Samsung USB Driver is already installed on your computer then Skip this Step
Step 2: Enable USB Debugging on your Android Smartphone. To enable USB debugging, Open Settings > Developers Option > USB Debugging > Tick to Enable.
(Developers Option is hidden for Android 4.2.2 or above, to show it Go to Settings > About Phone > Built Number (Tap on it for 5-8 times).
Step 2: Download and install vRoot Application on your Windows Computer.
Step 3: Once vRoot Application is installed on your Computer, Open It.
Step 4: Once vRoot Application is launched, connect your Android device to the computer.
Step 5: Once Your Smartphone is connected successfully to the computer, vRoot will automatically detect your Smartphone.
Step 6: Now, Click on the “Root” button to begin the rooting process.
Step 7: Now, vRoot will automatically “Reboot” your Smartphone and install the SuperSU Application.
Step 8: Now your Samsung Galaxy S2 SGH-I777 is Rooted. To check whether your phone is rooted correctly, open Applications Menu, there you will be able to see a new app installed, called SuperSU. If this app exist then it means you have successfully rooted your device.
Optional: You can also verify the root status of your device by using the Root Checker Application.
[*] No data loss process: Your Android Phone Data like contacts, pictures, videos, music and etc will be not affected with this method.
[*] Warranty Void: Your Samsung Galaxy S2 SGH-I777 AT&T Smartphone warranty may be Void after following the above tutorial.
[*] Samsung Stock Firmware: If you are looking for the original firmware for your device then head over to Download Samsung Stock Firmware for all devices page.
[*] Samsung USB Driver: If you are looking for the original USB Driver for your device then head over to Download Samsung USB Driver for all devices page.
[*] Credits: vRoot Application was created by Shenzhen (Developer).