Need more info.
When you turn computer on do you get any beep codes? When you turn it on and hold down any button on the keyboard, does it eventually start beeping at you? Does it make any windows sounds as it is booting that would lead you to believe it is booting up but just not displaying?
There is a VGA port on the left side for plugging in a monitor. If you eventually get video on it this would tell you your screen is bad and should limp you along until you get it fixed/replaced.
If you don't get video on the monitor either and you don't get any noises during boot that would tell you your computer is booting, you might have a bad motherboard. If this is the case this is usually not a cost effective fix unless you happen to know someone local, cheap, and skilled in repairing motherboards.
Let me know.