The PIN and PUK numbers are written on the card holder, usually:

This is from Tiscali, but with Wind and all operators it's the same.
If you don't have this you cannot find the puk, unless you call Wind, but they will ask you (in Italian) information about you and your registration and I'm not sure the merchant did register you correctly...
So, if you don't find the PUK you can also throw away the card and buy a new one when you get to Italy, insert it in the phone and enjoy it.