|when you switch on do you get an image on screen - and then it goes black when going into windows?|
if so, can you start in safe mode? switch on, keep tapping f8 key and when you get a menu select safe mode. it can take a long time to make it into windows in safe mode so be patient. once in windows in safe mode see if you can sort it out. safe mode is a trouble shooting feature where you get into windows without it loading most of the drivers.