My line is showing NO service

I was restricted from doing anything on my mtn line after linking my line with my NiN.

Dear Sir/Ma, I am writing on behalf of Olabay Marine Integrated Services Limited to request the provision of Closed User Group (CUG) lines for our staff. As a company...

I can't access my phone it keep showing me to Put PUK number. This happened while I was trying to do a sim lock from my phone settings