Advance payment made but no supply

Firstly, you will have to serve a legal notice to him asking him to repay the entire amount along with interest within 15 days of receipt of the legal notice

If he fails to make the payment even after receiving the legal notice,you can file a suit for recovery in Civil Court along with the purchase order acknowledgement receipt in order to recover your money along with compensation and interest.

Also, a police complaint can be given for the offence of criminal breach of trust and cheating against him.

For any other query, feel free to contact me at isidjain1@gmail.com

You can do lit many things legally if the firm really exists at the address. First make sure the firm exists at the address. If the firm is not at the address, file a Police complaint giving full details. If the firm is at the given address, contact a good Lawyer and through him issue a legal notice for refund of money. If no positive result, file suit giving full details. But, it may take a minimum of 5 years if not more before case is settled. Even if decree comes in your favour, you have to recover the money by executing the decree. That us the reality.

You have without any formal inquiries on such reputation parted with millions of rupees and now instead of getting a professional advise in person locally, you wish to depend on on line forum for free guidance.

It is too late.  Immediately entrust this to an advocate who is expert in dealing such matters.  There are many ways to recover the amount, and God knows whether you can recover full amount or not and when.  But, make a follow up..  The present directives of Govt will certainly help you.