Whille installing window 8.1 , i delete my system partition and formated primary partition as well then suddenly my installation failed . From that time onward i am unable to install os . . I try with window 8.1 which is not starting at all it is just showing sign of loading and also i try installing ubuntu it shows me error " please remove external media " press any key to restart , but i have no media connected to my laptop. ( i am using usb for installation)