Ok if you really want to know if the PC is dead or not, boot it up and press the NUMLOCK key. Does the NUMLOCk indicator light turn on and off? Yes, then it is booting, and you have a video problem. No, it is not booting, and you have a hardware issue with the motherboard more than likely! Now that is an actual best answer, and not guessing!
There are many reasons for such problem, for instance monitor is not working; video card is not working properly; simply dust; damaged cable; wrong connection; processor or motherboard malfunction.
If the computer boots and there are no bios sounds at the beginning, then it is likely that everything in the computer is in working order.
If there are two video cards, try to connect to the second one.
Disconnect the monitor from the computer, if there is no signal, there will probably be monitor not working itself.