There could be a couple of reasons why you are not getting a display. It could be the video card not working properly, a faulty or loose cable, or the monitor usually. If you have a video card and not integrated video (one that is part of the motherboard) take the card out of the expansion slot and reseat it. If it has power connectors attached to the card, reseat those as well. Also, reseat the video cable to the card as well as to the monitor. If you are using a VGA connector (usually has blue connectors on the cable ends) be sure that your monitor is set to use analog signal. If you are using a DVI cable, make sure that the monitor is set to use a digital input instead. If you have a different monitor, you can try swapping it out with the current one to see if that works. The same can be said for the video card. If you have a spare, you can try swapping it out with your current one to see if that works.
