what have you already tried,
are you using the computer that does not display to post this
is it a laptop or a desktop, have u tried pluging it into an external monitor (if laptop)
if desktop have u tried (if any) the other ports (for display)
run us through start up, does it display the mobo manufacturer what os
when does it stop displaying are you getting sound
has it ever encountered a large body of water engulfing it completely
any other details you think could be relevant?