WARNING! When you factory reset your phone, all data stored on the internal memory will be deleted, including contacts, apps, ringtones, downloaded content etc. In addition, all settings will be restored to factory values.

NOTE: Before resetting the phone, you can visit this thread for instructions on how to back up data, and this thread for a guide on restoring data. You can also check out this thread for more backup & restore options locally or via Google Drive.

Master Reset via Settings:

  1. On the home screen, open the apps drawer
  2. Go to “Settings
  3. Tap “Backup & reset
  4. Tap “Reset phone
  5. Optionally, you can enable or disable “Erase SD Card” (NOTE: when the feature is enabled, the SD card installed on your phone will be formatted, and all data on it will be lost)
  6. Tap “OK” to confirm

Master Reset Using Hardware Buttons:

NOTE: In case you are unable to reset the phone using the method above, you can try resetting it from the “HBOOT” menu. To access the menu you need to perform the following:

  1. Press and hold “Power” to turn off your phone
  2. Next, press and hold “Volume Down” and “Power” at the same time
  3. At the screen showing three Androids, release all hardware buttons
  4. From the “HBOOT” menu, press “Volume down” repeatedly to highlight “Factory reset
  5. Press “Power” to select the highlighted option
  6. When prompted, reboot your phone

Check for OS Updates:

NOTE: Once you factory reset your phone, it’s recommended to check if new OS updates are available for download.

  1. Tap “Apps” on the home screen
  2. Open “Settings
  3. Scroll to “Phone” and tap “About
  4. Tap “Software information
  5. Check if a new update is available, and if necessary follow the on-screen instructions to download and apply it

See More: HTC One A9: Factory Reset and Update the OS