ACER ASPIRE 7720 intermittent black screen please HELP!!!!!!!!!?

I was wondering if anyone could give me some advice, I have had an intermittent black screen on my acer aspire 7720 for the last few months, laptop works with external screen and sometimes (was more often) would turn on, the screen would boot up fine. but recently it hasnt booted up, the fn +f6 or f5 do not work at all and device manager does not show the screen, the other day I has the blue screen with recent hardware or software changes error and then it rebooted and my screen worked, the next time I turned it off it hasnt come back on again! I have took it apart and had a bit of a look, nothing looks split or unattached, please any help would be fantastic!