Airtel — Sim card registration get failed

Address:

j.k.pur,rayagada,odisha

I am using Airtel sim from last 10 years and suddenly 1 day a message reached and showing sim card registration got failed. on that phase no network activity shown to me .i have used same sim in other mobiles and showing sim card registration failed. i have tried to take new sim on the same number but it was showing someone else name.
now i want this number [protected] back, which was my main number