If you are getting a display when you hook up another monitor I would start by checking the cable to your current LCD. Below is a guild for replacing the LCD. Use it to find and verify that the cable connection your LCD to the board is attached and secure at both ends.
[guide|15281]
Did you recently drop it? The cable could also just be bad, the LCD could have died or there is still a chance there is something wrong with the board but that is the most unlikely. As a betting man my money is on loose cable or damaged LCD.