i accidentally scratched off the code

Yes. Just make sure to have the gift card serial number with you when you contact iTunes Support through:

http://www.apple.com/support/itunes/store/

This article may help too:

Invalid, inactive or illegible codes

http://support.apple.com/kb/TS1292

You will just need to submit a form to contact iTunes support. They will get back to you via email to resolve your issue. Email them the serial number of the card, and as many of the letters of the code as you can still read.

Instructions for that are here: http://support.apple.com/kb/TS1292

Here is the direct link to email iTunes:

http://www.apple.com/lae/support/itunes/contact.html

Hope this helps 🙂