But seriously, more details would be helpful so we can tell if something is not plugged in, the monitor is broken, the computer is broken, or someone painted your monitor screen glossy black.
What happens when you switch the machine on? Is there any sound at all (possible power supply failure)? Any beeping (how many in each bunch)?
What kind of computer / monitor do you have? Do you have another of either one in your house / place of work, so that we could try the monitor on a computer that is known to work to test if the problem is with the monitor?
By doing small tests to check one component at a time, we can isolate where your problem lies. Then we can address fixing it. I will keep a virtual eye out for detains from you.