A handheld mobile phone includes at least two buttons, a logic circuit, and a processing unit, wherein each button is used for performing at least one specific function. The logic circuit is coupled to the at least two buttons for generating a corresponding specific signal when one of the at least two buttons is pressed alone, and for generating at least a control signal when all of the at least two buttons are pressed. The processing unit executes the specific function of the pressed button according to the corresponding specific signal. When all of the at least two buttons are pressed, the processing unit controls the handheld mobile phone to enter a reset state from an operating state according to at least the control signal.