reset bios, turn off power supply, unplug, hold power button 10 seconds, take the motherboard battery out, wait five seconds, put it back in. turn everything back on
If you can see the bios: Get Display Driver Uninstaller. Boot Windows in safe mode. Run Display Driver Uninstaller and have it reboot the PC. Then once you install your new drivers, open Display Driver Uninstaller again and re-enable plug and play.
If you can't see the bios: Your PC might be using your onboard graphics, so try plugging the monitor into that. The PCIe slot could also be dead. Or it could be some other issue.