Please explain your problem more specifically - i.e. do you mean by the 'lock button' the one on the upper right side that can be set to control sound mute vs. locking the screen orientation? Or, do you mean the ON-OFF button at the right top? Is there any other damage to the iPad (e.g. screen cracks)? When did you buy the device which may impact on the warranty and potential for a replacement - good luck!