If you are on a desktop, Make sure all the power cords are unplugged from your computer.
Go inside of your desktop tower casing, look on the motherboard for a small watch type battery.
Take the battery out, then keep pressing the power on the desktop tower for a few minutes to make sure all the power is gone from the PC.
Then place the battery back in, start up the computer again, your bios/cmos should be reset to its defaults now.
Have fun!
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