Take your phone to a phone shop, cross their palm with silver (usualy about ten pounds) and they will unlock it for you, they can also set it with a new pin number. or no pin number if you prefer. The big highstreet shops might not do this (they don't know how to work half of the phones anyway) try a spcalist phone shop or you local market.
DONT PAY ANYTHING YET!! Just phone the customer service helpline of the network and they will give you your PUK.I did it in minutes with my Orange phone
Phone up your network provider. They will need your mobile number before they'll give you your PUK. You need to follow the manufacturers' instructions to the letter when entering the PUK. Also, if you enter the PUK incorrectly more than a fixed number of times (can be as low as 3 - usually 10) then the phone will block.
Good luck