Htc Niki Hard Reset
Hold the "call" and "end call" keys and use stylus to press reset on the left side of the USB port. The set will ask for confirmation. To confirm, press the "Enter" key on the keypad.
Warinig!!!!! this will delete all your data
Hold down Send and Reject Buttons and Reset with the stylus, release the stylus but keep holding the buttons till you see message : 'this will erase all your personal data' then press 'Action' (big front button)