Rav Belsky says copying your neighbor’s CD is permitted in this case:
QUESTIONER
If it (a CD you purchased – icot) breaks, and I hadn’t made a copy, can I borrow the same title from a friend, and then make a copy for myself?
RABBI BELSKY
If it breaks and you had forgotten to make a backup, does that mean you are now stuck, and have to go out and buy another original version of the tape or CD? I would say that you could act as if you had been wise and prudent in the beginning, and could make a backup now – by making a copy from someone who has one. The producer of the tape or CD doesn’t expect there to be two users who buy three originals. His intention is that there are two users who buy two original copies. You’re not taking away from his business, or causing him a loss.
I think it can be done because you had the right to do this before you lost it. You just assumed that you wouldn’t break or lose it.
source: http://www.torah.org/learning/honesty/question82.html
(finally, I can bring down a makil psak on this issue ?)