Desktop computer won't turn on but green light at the back stays on?

sounding like a motherboard issue. since you have the green led on the power supply. hope this helps. good luck

The motherboard. Need to replace it

The mother board might be blown. Try to plug it to another moniter to see if it comes on

Sometimes, after an outage, it will be 15 minutes before my computer turns back on. Give it a little more time. Also, have you confirmed that you turned your monitor on? Probably, but just double check? If you aren't hearing a fan, than it must be the CPU. Give it a little more time before becoming to worried. In the meantime, you could plug something else into the plug in to make sure it works. I don't know why it would'nt but if a circuit blew or something..

There isn't enough information to tell - please don't act on anyone's suggestion here - you might go out and replace your motherboard to find it's a completely different problem! You need to find someone IRL to have a look at it. Who knows, it could be something as simple as a loose connection to the power button lol. EDIT: look some of the suggestions given are ABSURD! Suggesting fixing a motherboard problem by plugging in a different monitor? blaming the "cpu" for no power? Can you say L-O-L?

It most likely is a power supply issue. try replacing the power supply. average power supplies run for about 20 to 40 dollars. If that doesn't work then you might need to replace your motherboard.