Today scratch the bar to see the code of the card and took off several numbers but not the middle if I could help because I cost 20 dlls and that Was expensive
The only thing I can usefuly suggest is that you contact Sony customer support, I can't promise anything but it's possible that they can see that the PSN Card has not been activated & just 'possibly' give you another code to use.
Here's the number for you, alternatively if you woud rather chat to someone live then plese click the 'live-chat' link in my signature.
Mon - Sun 6:00AM - 10:00PM Pacific
A PSN card is just a piece of plastic with a PSN code on it. If you destroyed part of the code by scratching too hard, and therefore don't know the code that you bought, then you are just out $20. Sony doesn't know which code you bought either, and won't give you a free replacement. You will just have to be more careful next time.