Pc doesn't show display or bios.

So I recently build my first pc and one day I was feeling curious and when my pc booted there was a option that said press F3 for bios unlocking and I didn't know what that was so I pressed it to see what is was and then my pc shut off.And now when I boot my pc the bios screen doesn't even pop up and there isn't any display but all my fans on my pc work and their isn't any beeps as well.Is this a problem with the motherboard or cpu?(btw the motherboard is a Biostar A780L3G and I have a Phenom 965)I know the psu and my graphics card work because i tested that on a other pc.