(Fastest Method)
If your flight is already cancelled, Indigo usually updates this link first before sending the SMS.

• Go to the IndiGo Plan B page on their official website.
• Enter your PNR and Last Name.
• If it lets you reschedule or choose a refund immediately, your flight is definitely cancelled.

2. Check the "6Eskai" WhatsApp Chatbot
The app is lagging for many people right now. Try their WhatsApp bot instead; it pulls data faster than the app UI.

• Save this number: +91 7065145858
• Send a message saying "Flight Status" followed by your PNR.

3. Government Helpline (New)
Since the cancellations are massive, the Civil Aviation Ministry just set up emergency control room numbers yesterday. If the airline isn't answering, try calling: 011-24610843 to confirm if your flight is on the cancelled list.

What is "Plan B"?
You mentioned "Plan B" in the comments. It is simply IndiGo's system that allows you to:

1. Change flight: Book any other flight (even 2 weeks later) for free.
2. Full Refund: Get your money back to the bank source (takes about 7 days).

My Advice: Check the status before you leave your house, and again before you enter the airport terminal. If it's cancelled, do not go to the airport. It is chaos there right now.