There are a variety of reasons your graphics card may not be working properly. The first thing to do is to try and troubleshoot the issue.
First, you should check the physical connection between the graphics card and your computer. There are several possible connection types, such as PCI Express, AGP, and PCI, so be sure that the card is plugged in securely. Also check to make sure the power supply is providing sufficient power to the card. If the card has additional power connectors, be sure to connect them as well.
Next, make sure your drivers are up to date. Most graphics card manufacturers provide updated drivers on their website. Be sure to download and install the latest version for your particular card.
If the card is still not working properly, it is possible that the card has failed. To verify, try another known-good card in your system. If the other card works, then the issue is likely with the original card.
It is also possible that there is an issue with the operating system itself. Try reinstalling the operating system or running it in safe mode.
If none of the above steps work, then it is possible the graphics card is damaged. This could be due to physical shock or corrosion. If this is the case, the card may need to be replaced.
Finally, if all else fails, contact the manufacturer of the graphics card to see if they can help. They may have additional troubleshooting steps or be able to provide a replacement card.