Intro: How to Repair an Arduino Board
In this instructable I'll show you how to fix an arduino board. The board got damaged about 6 months ago when I accidentally shorted 30V across the board ;-)
Luckily the power LED was still on, both of the voltage regulators were ok and so was the FTDI chip (responsible for USB connectivity). So obviously the Atmega chip got toasted. All that was needed was a new Atmega chip. In case you can get one that already comes with a bootloader just replace it and it's done. The video shows how to use another arduino board to burn bootloaders into ATmega chips or upload sketches to standalone chips.
wiring is here ->> http://arduino.cc/en/Tutorial/ArduinoISP