I lost a sim that I registered but my nin is not my own how do i retrieve my sim

I am in the United Kingdom. Recently, my mtn sim was lost.. I need to retrieve the sim. How can I retrieve the sim. Kindly, assist.

I need to retrieve that line to re-register my WhatsApp account, as the code keeps going to that line during the registration process. Kindly assist please. Many thanks

Benue state/ipole otukpa