Hp

My mother called me to come look at her computer.The computer boots up fine.But the monitor just had a blue screen,so i brought it to my house and hooked it up to my computer and the moniter would just go orange light.
I ordered a video card for it but it didnt make a differance.I bought her a new computer and am thinking about trying to get her old HP going if I can find out what is the matter with it.Any advise would be much appreciated.Thanks and God Bless