WARNING! Master resetting your phone will result in the deletion of all personal data stored on the internal memory, including downloaded content, media files, contacts, ringtones, apps etc. All of your phone’s settings will be restored to factory values. However data stored on the SIM and SD cards will not be affected.

NOTE: Before proceeding with the master reset you can visit the following thread and see how you can back up and restore data on the Samsung Galaxy A8.

Master Reset via Settings:

1. Tap “Apps” on the home screen
2. Access “Settings” and swipe to “Personal”
3. Tap “Backup and reset”
4. Optionally, enable or disable “Back up my data” and “Restore”
5. Tap “Factory data reset” > “Reset device”
6. Assuming your phone is protected by a PIN / password, enter the necessary info and tap “Continue”
7. Tap “Delete all” to confirm

Master Reset using Hardware Keys (Via Recovery):

NOTE: If your phone crashes, freezes, or otherwise prevents you from resetting it via settings, you can also try resetting it from recovery.

1. Turn off the smartphone
2. Press and hold “Volume Up”, “Power” and “Home” simultaneously
3. At the Samsung Galaxy logo, release the “Power” button but keep pressing the other two
4. When the Android logo appears, release all hardware buttons
5. Once you reach the recovery menu, press “Volume down” repeatedly to navigate to and highlight “wipe data / factory reset”
6. Press “Power” to select the highlighted option
7. Use “Volume down” to navigate to and highlight “Yes – delete all user data”
8. Press “Power” to select the option
9. Once the phone master resets, “Reboot system now” will be highlighted
10. Press “Power” to reboot your phone