Article in English: In order to access the Recovery menu, you will need to start with a powered down phone. Press and hold the Power button until the Power menu appears. Tap the Power icon to shut the phone down. Resetting your phone will erase all of the data on it, and should only be used as a last-ditch effort. If the phone is frozen, you can power it down by removing the battery from the back. Press and hold the Volume Down button, and then press and hold the Power button. Hold both buttons for about 30 seconds. Once the Android image appears, you can release the buttons. Use the Volume Down button to navigate the menu. Select “Factory Reset”, and then press the Power button to continue. The factory reset process will take several minutes.  When you select Factory Reset, your data will be erased. After the factory reset has completed, you will be asked to set up your phone as if it was new. If you log in with a Google account that was previously associated with the phone, and you had backups enabled, your settings will be restored.  You will be able to re-download any applications that you've purchased through the Play Store as long as you're using the same account they were purchased with.  Any contacts stored in Google Contacts will be synced to your account automatically.

Summary in Vietnamese:
Tắt nguồn điện thoại. Mở menu Recovery. Tiến hành bước Factory Reset (Đặt lại máy về Cài đặt gốc). Đăng nhập và thiết lập lại điện thoại.