Windows 7: Computer Tower Wont Turn on

Hi my computer is a windows 7 home premium 32 bit . My friend built it for me and im not very great with computers but i usually leave my computer on. It works fine its a great system and one day when i left with my friends to go fishing it was on but when i came back the next day it was off. So i went to turn it on and it wouldn't turn on. I unplugged it , plugged it back in and made sure the outlet was working . There are two buttons near the plug one that sais 115 and 230 and another one that has A , H , D i think or A , L , D but the switch for the first one is covering the 230 and 115 is showing . I have the O, I On I i made sure but even when i click the power button nothing will start. Theres a green light on the inside thats just a solid green light. Ive read around and people say that , that means the tower is receiving power. So i dont know what it is .. i have no real smarts with computers so i wont know how to remove anything from the inside or anything but i know that the fans are working i have 3 on the computer to keep it fine. I spun them and there all still fine. But there may have been a power outage while their gone could that have caused my system to stop working !?? would love any help i can get .

I guess one thing you could try is to unplug it, hold down the power button for about 30 seconds or so, let it sit for about 15 minutes, then plug it back in and try to start it.

I'm unsure what that means. Maybe if you post a pic of it...

Were any of the fans spinning by themselves when the power was on?

Yes all 3 spin when the computer is on

I did what u said the 15 min unplug and hold the button and still nothing ; ( its been off for 3 days and im tired of using my old crummy laptop anything else that u think i can try???

As it's a custom built desktop can you post the make/model of your motherboard?

What shows up on the monitor? Anything? Does it look like it's working but not getting a signal?

Everything is connected like it was when it was working? And you haven't changed any of the external switches (like the voltage switch you've already verified)?

No other LED's illuminate other than the single internal one on the motherboard?

I'm assuming the "O" and "I" mentioned below are the icons for the power switch:

but do you have any clue as to what the "A", "H", "D" are for? Or if it's really "A", "L", "D"?

Stating your case make/model number would be good, too...

It does sound as though it's been zapped and will likely require opening the case to go further, but please try to answer the above questions. This thread has close to 300 views, and the more details you provide the more likely you'll get more (or better) replies.