Please define "my screen doesn't even show anything" - do you mean the
screen is completely blank (i.e. no video output)? Have you checked to see
that your graphics card is correctly seated - and that the monitor cable is
screwed in? Any warning beeps - are you sure the processor is compatible
with the motherboard?
It is very hard for me - or anyone else come to that - to offer any advice
when we have very little information to base the advice upon.
Please post back with further details so that I - or someone else - may
provide more pertinent assistance.