Airtel — sim card stopped working

Address: New Delhi, Delhi, 110007

I am using my airtel sim from very long time maybe its been 4-5 years. But now it suddenly stopped working on 21 jan, 2020, it shows no signal, this is my sister's sim & she doesn't live in india now. I want to activate this sim because my bank account, paytm, & every other things are linked with this number. I went to the airtel store but they said i have to call my sister at the store but she doesn't live here anymore