Factory Reset:

WARNING! When you factory reset the phone, your personal data stored on the device’s internal memory will be deleted, such as ringtones, media files, contacts, downloads etc. In addition, all settings will be returned to factory values, but data located on the SD and SIM cards won’t be affected.

NOTE: Before factory resetting the phone, you can check this thread for a guide on backing up data, and this thread for a guide on restoring data.

Factory Reset via Settings:

  1. Open “Settings
  2. Access “Cloud and accounts” and tap “Backup and restore
  3. Optionally, turn “Back up my data” and “Restore” ON or OFF
  4. Go back to “Settings” and access “General Management
  5. Tap “Reset” > “Factory data reset
  6. Tap “Reset” and if your device is protected by a lock screen, enter your password/PIN and tap “Continue
  7. Tap “Delete all” to confirm

Factory Reset via Recovery:

NOTE: If your phone prevents you from resetting it via Settings, alternatively you can attempt to reset the device from Android Recovery.

  1. Turn the phone Off if needed
  2. Press and hold “Power” “Volume Up” and the “Home”/ “Bixby” buttons at the same time
  3. Release the keys at the Android screen
  4. Once in Recovery, press “Volume down” to navigate the menu until you highlight “Wipe data/factory reset
  5. Press “Power” to select the highlighted option
  6. Then highlight “Yes – delete all user data” and press “Power
  7. Finally, highlight “Reboot system now” and press “Power

Reset Network Settings:

NOTE: When resetting network settings, all of your saved network connections will be deleted, such as data restrictive settings, network selection mode, background sync settings etc.

  1. Open “Settings
  2. Go to “General Management
  3. Tap “Reset” > “Reset network settings
  4. If your phone is protected by a lock screen, enter your password/PIN
  5. Tap “Reset settings

See More: Samsung Galaxy J4 Core: Factory Reset via Settings/Android Recovery; Reset Network Settings