You need a paperclip, some screwdrivers, and patience
I fixed the same problem on a friend's laptop a while back. I couldn't think of any way to extract the pin from the outside of the laptop, but if you're not afraid to crack the case, the power jack is not sealed at the back. There are a couple slots that you can stick a paperclip in and push the pin back out. Since you'd have to remove that board anyway to replace it, it's worth a shot. You will want to buy a new power cord though.
Look for instructions on replacing the hard drive if you can't find anything on removing the DC in board, and just follow the steps until you remove the top case of the laptop (under the keyboard) and you can get at the back of the power jack. Then just use a paperclip or some other small pointy thing to push the tip of the plug back out.