Monitor won't display anything?

Ok, so i was helping my dad set up his computer in his new office and when I hooked up the monitor and turned the computer on, it did not display anything. He said the monitor had worked fine before but for some reason now it didnt. The monitor received power because the little blue light was blinking, but it would not display anything. We restarted the comp a few times and still nothing so i decided to take it home with me to see if it would work on my computer. It didnt... But i do know that it something wrong purely with the monitor since i plugged it in and my computer picked it up and set it as a second monitor, but it still didnt display anything, even after i restarted my computer a few time. I am not sure what else to do and any help would be greatly appreciated.
 
try changing cables for the monitor and make sure it was properly connected. Which interface are u using to connect the monitor, VGA, DVI, HDMI ?
 
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