If you enter the wrong PIN more times than the maximum number of attempts allowed, the card will become “PUK-locked.”
You need a Pin Unlock Key (PUK) code to restore access to
HTC Desire 520. Contact your mobile operator for this code.
On the Phone dialer screen, enter the PUK code, and then tap
Enter the new PIN you want to use, and then tap
Enter the new PIN again, and then tap