Hi- Though most monitors will work fine when installed as Plug N Play, or Default, some require an .inf file, like a driver, to be properly detected by make and model- the info that shows in the Device Manager. Most do not use separate drivers....
What your problem may be is that you have not installed the video card or onboard chip"s set of drivers....you need this to enable the Screen Resolution, or desktop size, settings and the color depth, like 16-BIT, 32-BIT, 256, etc. If you know the make and model of the computer, post it here....if you know the same for your video, whether it is an onboard AGP chip or an added in PCI video card, post that as well, we can point you to the drivers.
It may be on some of the CDs you have already. Here is a tool you can download called Belarc Advisor that may identify your video device so you can get drivers if you do not have them.
www.belarc.com
You want to use the Free Download link at that page. Just download it to the desktop and 2click to install it. Tells you lots about your system. Post back what you have, you can also open the computer and read the tags or labels on the chip or card.
Hint= look where the monitor plugs in....if it is on a card, you may have either an AGP card or PCI, the AGP slots are shorter and brown as opposed to PCI- white and slightly longer.
If monitor plugs to the row of ports like keyboard, mouse, etc it is an onboard chip. Your system paperwork or computer support site would be able to tell you- usually, just search on the model of computer you have.