MacBook Pro screen blank when turned on
So my MacBook Pro was working about 1 hour ago when I had left it on to do an update for one of my games on my desktop and I would think it would go to sleep. My MacBook Pro 17 inches 2007 model and I would think that when I got back home and opened my computer that it would awaken from sleep. This is where it gets weird the bottom half of my computer is on but the screen is turned of, I now that the computer is on since the light on the button you press to open the MacBook Pro is on. So if any one can help me I would be entirely grateful. So I have tried to restart it and that didn't work. I even looked up online if this had happened to other people and it has and I have tried restarting my MacBook Pro on safe mode by pressing the shift key and that didn't work. Then I tried restarting the PRMA and that didn't work. The same thing has happened to my sisters computer which is an identically MacBook Pro like this one in every way and she sent it to apple and they said that you have a bad logic bouts and now they have to replace and those are very expensive and I am just hoping that I don't have that problem with my MacBook Pro. So if any one can help please. Ohh my computer runs osx but I think it's to the most updated osx but not mountain lion. If anyone needs anymore information about my computer to help me fix this problem I will gladly give you more info thanks and please help.
MacBook Pro