How to Restore Galaxy Devices to Factory Default Settings

If your mobile phone is slow, keeps freezing, doesn’t work, respond as well as it should or want to refresh the system performance, it may help to take it back to factory default settings.
Resetting your phone to factory default settings erases all your stored data, applications and configurations you’ve made on the internal storage of your mobile phone, so try to back up your important data first and save it to your computer or your external storage.

There are two way to reset …
Method 1 (if your device is able to boot) :

1. Go to : Settings > Accounts tab > Backup and reset.
2. Tap Factory data reset > Reset device > Erase everything.

Method 2 (if your device in boot loop) :

1. Turn off your device
2. Press and hold Volume Up, Home and Power buttons at the same time.
3. Release the Power button but continue to press and hold the Volume Up and the Home key, when it vibrates or display the model number of your phone.
4. Release Volume Up and the Home key, when the Android logo appears.
5. Scroll down by Volume down key to “wipe data / factory reset” and select by Power key.
6. Scroll down and select “Yes — delete all user data” to start the master reset.
7. Select “reboot system now” to reboot your phone to its factory settings.

Your device will take 2:3 min (not more) in configuration, so don’t panic if you wait few minutes.