Computer turns on but no display on monitor

[frankdatank16]

I have a custom computer i built about 3 years ago but I took a break this summer then I tried turning it on and nothing popped up on the monitor but my computer was running and lights were on. Please help

 

[ficler1977]

plug a monitor from other computer(onto hdmi or VGA port) so You will know if laptop works. you can also use a torch to check if screens light stopper working(put some light on screen).
sometime laptop itself works but screen is dead. or screen works but screen light is broken(displays but extremely dark that you have to flash she screen using torch).

When laptop starts can You see anything os screen is black all the time. sometime screen hows up on start but disappears when windows is loaded. please provide this information(if screen is black all the time)