I was have Windows Vista operating system. Just spoke with my provider last week about computer continually disconnecting and reconnecting to internet. Problem was solved. Now when computer is turned on, screen is black but seems to try to initiate with green light, then immediately turns to amber and will not come on. I unplugged and reattached everything to see if screen was bad- screen still tries to initialize with green light then immediately turns amber and will not come on. Any of you ever have this problem? What steps do I take to correct it?
Any advice is highly appreciated!

Is it LCD, or CRT monitor?
Restart to Safe Mode (keep tapping F8 key after restart), and see, if it works there.
If not, try monitor in another computer.

How was the previous problem solved?

Was the computer opened?

Did it ever work after the previous solution?

It sounds like your BIOS is not even POSTing.

Do you hear any BEEPS?

Often after the monitor light goes from green to amber you get the message: "No Signal Input".

In most cases this is a hardware problem and the first step would be reseating your RAM.

Are you familiar with working inside the box?

Unfortunately, Safe Mode won't work because that is a trimmed down version of Windows that is loaded from the hard disk, way past the point in the boot process from seeing something on the monitor.

But I agree to try another monitor, and/or try that monitor on another computer. If the two monitors don't turn on, it's the computer. If the problem follows the monitor to the second computer, it's the monitor.

Other options include graphics card not fully seated, the cable connections, including the ones in the back of the monitor (if not hard wired) are not tight.

Also, you said it was just worked on - many motherboards have an extra power connection for such things as on board graphics, and many graphics cards require an extra connection too - you need to make sure all power connections securely fastened.