i had recently bought a new case. so i wanted to put all my stuff from one case to the other and make it pretty and fancy. well when i go to put it in it was backwards or something; pissed me off, but w/e. so onto the question.
I put everything back in the original case. and it turns on. But the video display wont show. the fans and everything kick on. and i tried to use my graphics card instead of the integrated one and it didnt work either.
also the lights on my mouse and keyboard wont light up.
More aboutmight fried mobo
check all connex. reinstall all cards, mem, etc
something is loose, or looks like it is installled properly but it isn't
or you broke it or static discharged or all sorts of stuff - but usually, check all connections - rule of thumb.
Pull all of the old parts out of the old case. (You need to do this anyway.)