monitor won't start up

I don't know what the monitor is supposed to do when loading, i've never been able to use it before. And yes my computer is on (i'm not that dumb that i didn't try and turn on the computer too) I have an old IBM 15" monitor sitting next to it now that i've been using up til now and when i plug that one in, everything works fine. I've tried fiddling with settings, loading drivers for the new monitor, pretty much anything that a semi-intelligent computer user would do in order to try and fix the problem. I've changed settings, restarted the computer but nothing works so far that i've tried. I've also noticed that if i plug the "new" monitor in and turn it on it proceeds with the problem that i described in my first post (it's almost as if it's trying to turn on but then it turns off before it can and then back on) but if i unplug the actual video cord (15 prong cord thingy) that the monitor will only flash between the green and orange lights and not turn off as well? could this be a clue to something? please help anyone, i'm sick of using a 15" monitor and my eyes would love to see the "new" 19' one working soon. Thanks again to anyone that can help me with this