HP Pavilion won't power up.

Sorry posted this in the wrong section so im reposting it.

Well today i tried to turn on my hp pavillion a1440n and it wouldn't turn on. NOTHING happens when i press the power button. The fans don't spin teh power button doesnt light up, nothin. There is absolutely no sign of life. The only remote sign of life is that the tiny green light on the back of the power supply is glowing. i tried a different outlet that i knew was working and still no luck. I also tried to drain the power by unplugging it and holding the power button and still no luck. It was working fine last night. I'm thinking it's a PSU problem? an anyone confirm for me? The entire computer is stock except for an additional 1 gig of ram i added and the nvidia geforce 9500gt graphics card i added about 4 months ago. Thank you.

ps- sorry for the double post but the psu is a Hipro HP-d3057f3r and i'm typing this up on my ancient computer so please excuse the innumerable typos.

there isnt a switch at all. there's only the voltage toggle which i know i set correctly

Umm, you want him to pull the battery and turn his PC upside down??