FlowRez :
I tried but the pc won't boot after restart therefore i couldn't save the settings to boot from a flash drive
You were saying something about overclocking, did you and then the issue started? Not really sure what you are explaining here, you turn on the computer and what happens? No display? Or is the issue only when you try to get into Windows then it never loads? You keep saying "restarting" are you saying from a cold boot with the power off you have no display or it just does not reboot normally? Can you get into the BIOS at all?
Try resetting the BIOS to defaults using the motherboard jumper, if you have an add-on video card remove it and use the onboard video.