I have bought a gift card for my friends birthday and she scratched some of the code off, how do i get the code back? what do i do?

If this page doesn't help then you will need to try contacting iTunes support (you will need to give them as much of the serial number and activation code from the card as you can read) : http://www.apple.com/support/itunes/contact/ - click on Contact iTunes Store Support on the right-hand side of the page, then iTunes Cards And Codes