Can 50Rs Stamp Paper used as an Agreement?

Hi, I will try my best to explain the situation briefly. I took a project from one of my friend in December 2020 and he owns a start-up BPO company, He made me invest around 20Lakh rupees into the business till date which includes (Office Space, Employees Maintenance, Interests of the Loans I took to do this business, Office Maintenance, Computers, Furniture ... Etc) But he never handed over the project to me, he keep on postponing it for an year giving me various reasons like Covid 2nd Way, He's Personal Health Issues and all. But I finally came to know that he's been bluffing all time and cheated me so I demanded him to give all of my money back which is being invested by me Till date. He agreed upon this but he isn't willing to pay everything I invested even though he's the one who made me do it, I have all the proofs including call records, Text Chats and all. But we never did an agreement till now and now I'm in so much debt that I couldn't make out of it if he doesn't give the money to me. Is this 50rs stamp paper works for this kind of procedure or can I do something else to get my money back ? Please help me out in this I don't know what to do and he's been playing around with me