WARNING! When you factory reset the device, all of your personal data stored on the device’s internal memory will be deleted, including media files, ringtones, contacts, downloaded content etc. In addition, all settings will be restored to factory values. However data located on the SD and SIM cards won’t be affected.

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

Factory Reset via Settings:

  1. Launch “Settings
  2. Go to “Personal
  3. Tap “Backup & Reset
  4. Optionally, enable or disable “Automatic Restore” and “Back up my data
  5. Tap “Reset phone
  6. If your phone is protected by a lock screen, enter your PIN/password
  7. Optionally, you can choose whether or not you want to “Erase SD Card” too
  8. Tap “OK” to confirm

Factory Reset via Android Recovery:

NOTE: If your phone crashes, freezes, or otherwise prevents you from resetting it via Settings, alternatively you can try resetting the phone from the Android Recovery menu.

  1. Turn the phone Off if necessary
  2. Press and hold “Power” and “Volume down” simultaneously
  3. When the phone vibrates, release “Power
  4. At the “hTC download” screen, release “Volume down” too
  5. From the hTC download menu, press “volume down” repeatedly to navigate the menu and highlight “Reboot to bootloader
  6. Press “Power” to select the highlighted option
  7. Use the volume key to highlight “Boot to Recovery Mode” and press “Power
  8. At the “No Command” screen, press and hold “Power” and “Volume down” at the same time
  9. Once in Android Recovery, release the buttons
  10. Use the volume buttons to navigate the Recovery menu and highlight “Wipe data / Factory data reset
  11. Press “Power” and highlight “Yes – delete all user data
  12. Press “Power” again
  13. Once done, ensure “Reboot system now” is highlighted and then press “Power

See More: HTC Desire 12s: Factory Reset via Android Recovery or Settings