- If laptop:
It may / may not be integrated. Either way it's extremely hard to take a laptop apart and extremely hard to source a replacement mini video card. It could be a fault with the flat screen. If the laptop is very new then there is a chance of space parts, otherwise you've got a hard job on your hands sourcing 2nd hard stuff. If it's a screen fault you should be able to plug in a normal monitor in the back.
- If normal PC:
If the monitor socket is on a card slot then it has a separate video card you can replace - otherwise it is integrated on the motherboard.
If integrated you may still have a chance to fix it. Open up the PC case (provided this doesn't affect any warrantee). If the motherboard has a video card slot then you might be able to change the "on board video jumper" so that the integrated video is disabled - and then you can fit a new video card in the free video card slot. HOWEVER, there are lots of different video card slots (you will have to read up on Wiki about them to identify what you'd expect on your computer) and you would need a user manual for your motherboard to identify the jumper (download-able from the motherboard manufacturer).
If it's a big name branded PC (with a branded Windows CD not an MS one) then it may be best to grovel at there customer support for help. Often, because they know your computer better than you do, they can help you faster than any old computer shop.
Paul
June 2007