First of all, I know I should have just left well enough alone. I'd been trying for hours to install updated drivers for AMD Catalyst, but it timed out every time. So, one site suggested uninstalling old drivers before installing new ones. I followed the steps on the AMD website to uninstall, and suddenly my screen went black. I've tried switching from HDMI to a standard pc port on my screen, but nothing works, and now I can't even see anything to enter safe mode and get the updated drivers.