|with the monitor connected to your computer - when you power up the computer (ensure the monitor is switched on first) do you see "anything" (even if only briefly) on the screen?|
Can you connect the monitor to another working computer and see f the monitor does the same thing there?
And per chance can you borrow another known to be good monitor and connect that to your computer?
The two above tests are an effort to discover if the problem is within the monitor - or the computer...
Also do you have another cable to connect the monitor to your computer (presuming your monitor doesn't have a permanently attached cable...; and thus rule out (or in) the monitor cable...?