firstly do you have another computer to test the monitor on? also do you have another monitor cable you can test going to your pc? probably best to narrow down that there is actualy something wrong with the monitor before you go and buy a new one, if could even be a graphics problem, does the monitor not display anything? not even before booting up to windows?
my guess would be that it could be a problem with your monitor cable as the mintor turns on with a green light.