Ok I have an at&t Motorola c1681 go phone and i left the keys unlocked and put the phone in my back pocket i took it back out to make a call and it was asking me for a PUK code? what is that and what should I type in? Please help i'm desperate

Complete information :
The SIM card protects your subscription and not the phone from unauthorised users. If you change SIM cards you can still use your phone with a new SIM card. Most SIM cards are blocked at the time of purchase. If your SIM card lock is on you have to enter your PIN (Personal Identity Card) every time you turn on the phone.

If you enter the wrong password three times in a row the SIM card gets blocked. This is indicated by the message PIN Blocked To unblock this you need to enter your PUK

Note:
card (Personal Unblocking Key). Your PIN and PUK is supplied by your service provider. You can edit your PIN and select a new four to eight digit number

• If the Message Codes do not match appears when you edit your PIN you entered the new PIN incorrectly.
• If the message Wrong PIN followed by Old PIN appears then it means that you have entered the old PIN incorrectly.
  

1. When PIN Blocked appears enter your PUK > OK
2. Enter a new four to eight PIN > OK
3. Re-enter the new PIN to confirm > OK
   

1. > Settings > the General tab > Security > Locks > SIM Protection > Change PIN
2. Enter your PIN > OK
3. Enter a new four to eight digit PIN to confirm > OK
   

1. > Settings > the General tab > Security > Locks > SIM Protection > Protection and select On or Off
2. Enter your PIN > OK