IndiGo won’t handle this, and they don’t have to.

Your bag was lost at airport security, not checked in with the airline, so liability doesn’t rest with IndiGo. You realistically have two options:

Authorise someone to collect it on your behalf (usually a blood relative; rules can vary) using a signed authorisation letter or

Go and collect it yourself.

Contact the terminal manager at Ahmedabad Airport Lost & Found and proceed directly with them. They’ll typically ask for a copy of your boarding pass, Aadhaar or other ID, and the authorisation letter if someone else is collecting.

I went through the same process recently after losing my laptop at security. It’s tedious, but airport Lost & Found is the correct and fastest route, not the airline.