|I suspect the display-adapter (also called a graphics card) has failed inside the computer that the monitor does not work on. In which case, you need to replace it with a new one.|
If the existing (failed) graphics adapter is integrated "on-board", you need to disable it in the BIOS Setup before fitting a new one into a spare PCI or AGP slot (whichever type of slot is available).
The reason for disabling the integrated graphics adapter is because it cannot be physically removed. Disabling it is necessary to prevent the system from detecting it in future.