My Computer flashes different colors every time I play a game. How can I fix this?

I have a touch screen desktop computer and every time I try to play The Sims 2 or roller coaster tycoon or any other game that takes up the whole screen, my computer flashes different colors and I am not able to get out of it unless I unplug my computer. I know that the graphics card is messed up but I have been told that there's no way to fix it. Can someone help me and tell me how to fix it, if it is repairable?