1. Input a wrong password so that system display a window with error messasge
2. Pls use the mouse click on this window, use your mouse interchangeablely "left click"-"right click"-"left click"-"right click"-"left click"-"right click"....pls 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 password.