Hi Jenny, you've had a 4 digit pin code on your sim card which you've guessed wrong 3 times in a row, it then would have asked you for a PUK code. Your PUK was available from your service provider free but now you've tried to guess the PUK & blocked your sim..
Either a new sim or speak to your service provider & they will sort it for you.
Hope this helps
GATORS
Craig, October 2008