Does it say "no cable connection" or "no signal"?
it says no cable connection
Based on the information supplied, I'd suggest a process of elimination. Check that none of the pins are bent on the VGA cable (where it connects to the computer).
Try the monitor on a known working computer. At least this may rule out the monitor as the problem.
Does the machine have on-board video or a video card? If it's on-board, you may be able to use a video card. Be sure to disable the on-board video (in the BIOS). The choices of video card depend on the available types of slots on your motherboard.
Please let us know if you found someone's advice to be helpful.
Does anything else show on the screen before or after that message?