No, a defective HD is not likely here.
Much more likely is the failure of the video card.
If you can "borrow" a suitable plug in card and try that it should prove where the fault lies.
It is possible though not certain that you might have integrated graphics as well as the video card, in which case remove the plug-in card and see if the picture returns. (If you do have this alternative, you may have to enable the on-board card in the BIOS first.)