Much like a computer, a GPU can be repaired. The issue is that it often costs more to fix an old unit than to purchase a new one. It really depends on how broken the system is, the time spent getting it fixed, and the cost of the new GPU compared to what you have in your possession currently. These days most AAA games run fine on Nvidia GeForce GTX 200 series so chances are if your GPU is from 2001-2006 then something needs to be replaced or upgraded anyway since they cannot handle DirectX 11 or 12 for the vast majority of games that take advantage of these features which includes many indie PC titles as well as some larger-scale productions such as Stardew Valley and Homefront.