Look, the reason I asked that was because every computer is different. Knowing what kind of computer you have and what's in it is the first step. Before that, we can't help you very well.
I'm sorry if I came across as mean. That wasn't my intention. I wanted to help you, I just needed more info to go on.
What I want you to do is try to start the computer in safe mode. There's usually a screen right when you turn the power on with a logo of some sort. Press F8 and that should bring you to some options where you can boot into safe mode. You have to be quick and ready to press it because it might disappear kind of quickly.
That MIGHT get your computer to display the screen again in safe mode. Usually, safe mode only loads up the bare minimum in terms of software and drivers so this may get your computer to display something. But ONLY in safe mode.
If safe-mode shows you something, then what I would want you to do is install some new graphics drivers. Every part of your machine has some software that's called a driver. It's what helps to tell each part what to do and how to do it. You can find the driver for your graphics card on the Nvidia website. Nvidia is the maker of your graphics card.
http://www.nvidia.com/Download/index.aspx?lang=en-us
You have the GeForce 6150. So go to the download drivers section that I just linked you to, and select GeForce 6 series under the "Product Series" section. Then choose your operating system, and click download.
You'll get a setup file. Run that file, and it should install some new graphics drivers for you. Then restart the computer and boot it regularly. This might help you out.
Let me know how this goes.