Timothy, post the laptop manufacturer, and the laptop's model number. It's on the bottom of the laptop, Usually in a sticker, or white Service Tag.
This way I can guide you in more detail. Post back in a Comment.
A) Laptop OFF, monitor OFF, connect a VGA monitor to the VGA connector, on the laptop.
This is an example of a VGA Cable, and VGA connector,http://en.wikipedia.org/wiki/VGA_connector
Could be on one of the sides of the laptop, or the back of the laptop.
You can use a CRT monitor, (Looks like a small TV), or a flat LCD screen monitor, that has a VGA cable attached.
B) Turn the monitor on. If a CRT type allow it to warm up.
Turn the laptop on.
By default the display should show on the external VGA monitor.
There are at least three display options available:
1) Internal monitor of laptop ONLY
2) Internal monitor of laptop AND external VGA monitor
3) External VGA monitor ONLY
Press, and hold down on the Fn key, and at the same time tap once on the Display Toggle-Over key.
Which one is it? Dunno. You didn't state what laptop manufacturer, and model number.
It is one of the F1 through F12 keys. Most of the time the F4, or F5, or F7 key. Has a monitor symbol on it, and sometimes a side arrow.
No display on external monitor still?
Hold the Fn key down again, and at the same time tap once more on the Display Toggle-Over key.
If the display still does not show on the external VGA monitor, you have a bad graphics chipset on the motherboard. Usually means motherboard replacement.
(There are problems with HP Pavilion dv2000 series, Pavilion dv6000 series, and Pavilion dv9000 series, in this area. There are other model series of laptops also, not just HP. There is a solution besides motherboard replacement)
C) IF, the display shows on the external VGA monitor, you have a problem with the Video Cable, or inside the Display Assembly.
I can help you find it, just need the laptop manufacturer name, and Model Number.
Post back in a Comment.