My sim is block, how do I get my puk code to unblock this number 08142401380?

With an alternative phone number, Dial *123*7*3# or dial *123# (MTN’s self-service USSD dial) and follow the prompt of inputting ‘7’-Self-Service, then ‘3’-Get your PUK code to access the service.
You will be required to answer 3 questions to validate ownership of the line. When answered correctly, the PUK Code will be displayed on the 3rd party phone and SMS shared also.