I know it was a really stupid thing to do but i pulled the plug while the computer was on. Now it won't start up at all. What should i do? How can i fix this? What did i do to it?What does it do when hit the power button?  Do you hear any fans running, any noise at all?nothing happens at all when i try to turn it on. There is a blinking green light in the back of the CPU or whatever. I don't know what that means. But nothing happens at all. Did i fry something?Why did you pull the plug?  How soon did you plug it back in after you first UNPLUGGED it, almost immediately, or after a few minutes or longer?  Do you plug it into a surge protector or directly into a wall outlet?  

What brand and model is your computer?i plugged it in i think a few minutes after. It's a Dell. I plugged it into the outlet. What do u think is wrong with it?I believe you may have fried something.  The damage may be limited to the power supply (PS) unit  inside your computer or might inlcude the motherboard or other components.  I suggest you take it to a repair and TELL them what happened.  

Replacing a Power Supply is not difficult for anyone who has some experience upgrading computer components.  I recently REPLACED a PS to upgrade from one rated 250 Watts to one rated 400 Watts.  So, it can be a do-it-yourself project if you've had some experience installing or upgrading hard drives, CD drives, memory, sound cards, video cards, etc.  

But, again, the damage may go beyond the power supply and some TROUBLESHOOTING and testing may be necessary.  A repair shop is going to be best equipped to do that.

And, by the way, always plug your computer into a good surge protector, not directly into a wall outlet.  A reference: http://www.howstuffworks.com/surge-protector.htm
May I also suggest the following:

Look at the back of your computer (the Tower) where the power cord plugs in
Is there a switch there with a I or O in it? Switch it to the O (off) then to the I (on) and then try starting it up by pressing the front power button if it doesent start already.