1. Input a wrong password so that the system displays a window with the error message
2. Please use the mouse click on this window, use your mouse interchangeably "left click"-"right click"-"left click"-"right click"-"left click"-"right click"....please do this at least 12 times.
3. Then it will pop up another window, "restore default user", Click YES to restore system so that password comes back to default one. The default password is none.
You don't need to input anything as the password.