Well, coincidentally the same thing started happening for my dads laptop today.
I've tried a lot of fixed but to not avail.
1) Tried to connect to external monitor
2) Swapped memory to other slot but for some reason it didn't fit in the alternative slot
3) Plugged off power and removed battery then held power button for 60 sec etc.
Nothing helped so far. If someone has tips then please, I could use them aswell.
I once had that problem with a laptop. I was able to see the screen if I looked closely while shining a flashlight into it.
In cases like these, your best bet would be to take the laptop to a computer repair shop. I thought it might have been the inverter that went out (up to $50 fix) but the shop said the entire screen needed to be replaced. However, they only charged me around $100 to replace the 17" screen... so it was worth it.