Case of fraud

I had taken a loan in 2011 and given it to an office colleague who was a friend. He was supposed to invest the money in the stock market and had promised me a fixed rate of interest (Irrespective of market conditions) +The emi amount every month on the 1st. He had started a company and provided me with a written document (On the company Letterhead) stating the amount he would pay me every month and that the loan would be his responsibility. For the first couple of months he paid me small amounts that were less than the committed amount and then stopped... Now it has been 8 months since he last paid me a single penny. Additionally over 17 months of payments have not been made by him. Also I transferred the loan money to his account via an online account to account transfer. I have made several attempts to call him and also messaged him on whats-app to no avail. He refuses to co-operate and pay me back the money stating he had incurred losses and will pay me in a few days. And over a year and a half has passed with these excuses. In an attempt to resolve the matter peacefully I also tried speaking with his father but that has not helped either. I am really frustrated and wish to take legal action against this person now. Before i do so. I just wanted some guidance as to how i can go about recovering this money as i lost my job about 6 months back and have been without a job for a while now. I have been unable to pay the EMI for the past few months and the bank people are coming to my place, further adding to my stress and embarrassment. All i have as proof is the company letter stating the commitment made for the investment, The online money transfer statements and whats-app conversations. In desperate need of help.