Monitors and Graphics Cards

Monitor
A computer display, monitor or screen is a computer peripheral device capable of showing still or moving images generated by a computer and processed by a graphics card. Monitors generally conform to one or more display standards. Sometimes the name "display" is preferred to the word "monitor".

Graphics Card
A peripheral device that attaches to the PCI or AGP slot in your computer to enable the computer to process and deliver video. Once installed in the computer, a cable is used to attach the graphics card to a computer monitor. Graphics cards can also be 'onboard', built into the motherboard.

Nothing displayed on the Monitor
Check the monitor power button is set to on and that the monitor lead is in the back of the computer in the relevant socket.  Does the PC have power; is it making the usual start-up noises? If not it is possibly a PC issue rather than a monitor one.