|Plug the external monitor's video cable into the VGA port when the computer is not running. |
Switch the external monitor on.
Try to boot the computer.
Some laptops will display on an external monitor without you having to do anything.
If you get no video on an external monitor, some laptops have a key combo that you must press to toggle the display to external video only / sometimes both / built in display video only - see the Owner's or User's manual for the model.
If there are problems with the video on an external monitor, you have a problem other than with the built in display.
See response 2 in this - try cleaning the contacts on the ram modules, and making sure the modules are properly seated:
For a laptop, or netbook, you must remove both its main battery and AC adapter before you do that.
For a brand name computer, see the Owner's or User's manual if you need to - how to remove or replace the ram is usually in that - it may already be in your installed programs. If you can't get into Windows, it may be on a disk that came with the computer, or you can go online and look at it or download it - it's in the downloads for your specific model.
If there is nothing significant wrong with the battery or AC adater or it's connection or the DC jack in the laptop, or the connection of the ram, then the video adapter built into the mboard is damaged and you must replace the mboard in order to fix the problem.