Hi try this, goto "DEVICE MANAGER" on "MONITOR" make sure it is "Generic PnP Monitor" if not, Uninstall(cheek delete..) it. and click Scan for hardware change.
Love you so much MOSESKING,
i did all other solutions, but urs, fixed my prob.
in case ny one else faces such prob, here were the solutions:
1. updating intel/nvidia/amd graphic drivers from your own provider
2. update drivers from generic manufacturers
3. in vaio laptops, disable its power management
4. in asus/lenovo updates its firmware and special software related to monitor/graphic card/Fn keys.
5. try disable intel graphic --> reboot --> enable it again --> reboot
6. restoring windows to a previous settings
7. sometimes refresh/reset windows 8/8.1
8. uninstall any power management software and do a fresh install
Hope it helps all others, as it took me to download over 3GB data and solved prob only by following MOSESKING solution