Also, check the video adapters. If you have vga/dvi/hdmi/svideo etc, try finding a capble and connecting it to an alternate monitor/tv. If it displays on the external device, then the video chipset/GPU is still good and there is an issue with the monitor itself. If it doesn't display on the external device, then the video chipset/GPU is probably in disrepair. Alternatively, if the external device does display your video chipset/GPU output, then there is most likely an issue somewhere in between the video chipset/GPU.
Troubleshooting 101.
If you determine the issue is with the video chipset/GPU there really isn't anything that can be done other than replacing that part. If the issue is between the video chipset/GPU then you will want to check the cables, and the connectors. Do not spray anything into the connectors. If there is corrosion built up on the connectors, you will need to replace that part if possible. If the cable is damaged, burnt, or frayed, you will need to replace that.
Keep us updated, if you can diagnose the issue yourself, you can probably end up saving money in the end.