Reset Network Settings:

NOTE: When you reset network settings, all your saved Wi-Fi and Bluetooth connections will be deleted. Additionally, data restrictive settings, network selection mode, and background sync settings will be restored to factory values.

  1. Launch “Settings
  2. Access “General management
  3. Tap “Reset” > “Reset network settings
  4. If the device is protected by a lock screen, enter your PIN/password to proceed
  5. Tap “Reset settings

Factory Reset

WARNING! When you factory reset your phone, all your personal data stored on the device’s internal memory will be deleted. This includes contacts, ringtones and other media files, downloaded content, apps etc. Furthermore all settings will be restored to factory values, however data on the SD and SIM cards won’t be affected.

NOTE: Before you reset the phone, you can check this thread for a guide on how to back up app data, contacts, and media files, and this thread for a guide on restoring data.

Hard Reset via Settings:

  1. Open “Settings
  2. Go to “Sound and accounts
  3. Tap “Backup and restore
  4. Optionally, enable or disable “Back up my data” and “Restore
  5. Access “Settings” and tap “General management
  6. Tap “Reset” > “Factory data reset
  7. Tap “Reset device
  8. In case your phone is lock-screen-protected, enter your password/PIN and tap “Continue
  9. Tap “Delete all

Hard Reset via Android Recovery:

NOTE: If your phone prevents you from resetting it using the method above, alternatively you can try resetting it from the Android Recovery menu.

  1. Ensure the phone is powered off
  2. Press and hold “Home” and “Volume Up” at the same time, then press “Power
  3. At the Android screen, release the buttons and wait for the Recovery menu
  4. Press “Volume down” repeatedly to navigate the menu
  5. Highlight “Wipe data/factory reset
  6. Press “Power” to select the highlighted option
  7. Highlight “Yes- delete all user data” and press “Power
  8. Once done, ensure “Reboot system now” is highlighted and press “Power

See More: Samsung Galaxy J8: Factory Reset via Settings or Android Recovery