Reset Network Settings:

NOTE: When you reset network settings, all saved Wi-Fi and Bluetooth connections will be deleted, while data restrictive settings, background sync settings, and network selection mode will be switched to default.

  1. Open “Settings
  2. Go to “General Management
  3. Tap “Reset” > “Reset network settings
  4. In case the phone has a lock screen, enter your password/PIN to proceed
  5. When ready, tap “Reset settings

Soft Reset via Hardware Keys:

NOTE: A soft reset simulates the removal of the battery. This can be used when the phone is unresponsive, and won’t delete any personal data stored on the phone.

  1. Press and hold “Power” and “Volume down” simultaneously
  2. Keep the buttons pressed for up to 45 seconds
  3. When the phone finishes rebooting, release the buttons

Hard Reset

NOTE: Hard resetting the device will result in the deletion of all your personal data stored on the phone’s internal memory, including ringtones and other media files, contacts, downloaded content etc. Furthermore, all settings will be restored to factory values, but data located on the SD and SIM cards won’t be affected.

You can check this thread for a guide on how to back up data before the reset, and this thread for instructions on how to restore data.

Hard Reset via Settings:

  1. Open “Settings
  2. Tap “Cloud and accounts
  3. Access “Backup and restore
  4. Optionally, you can enable or disable “Restore” and “Back up my data
  5. Go back to “Settings” and access “General management
  6. Tap “Reset” > “Factory data reset
  7. Tap “Reset device” and if necessary, enter your lock screen password/PIN
  8. When ready, tap “Continue” > “Delete all

Hard Reset via Recovery:

NOTE: If your phone freezes, crashes, or otherwise doesn’t work as intended and prevents you from resetting it via Settings, you can try resetting the device from the Android Recovery menu which can be accessed by performing the following steps:

  1. Turn the phone OFF
  2. Press and hold “Home” and “Volume Up” at the same time, then press and hold “Power” too
  3. When the Android logo appears, release all the buttons and wait to gain access to Recovery
  4. In Recovery, press “Volume down” repeatedly to navigate to and highlight “wipe data / factory reset
  5. Press “Power” to select the highlighted option
  6. Press “Volume down” to highlight “Yes – delete all user data
  7. Press “Power
  8. Once done, “Reboot system now” should be highlighted. Press “Power” one last time to confirm and reboot the device

See More: Samsung Galaxy S9: Soft/Hard Reset via Settings and Android Recovery