Vehicle purchase agreement- Not return the advance amount

Dear Sir/ Madam, I given advance 12lakhs to one person for purchase 2 buses. I gave 2 times by splitting the amount 5lakh, 4 lakh and 3 lakh already he has to give me. When I gave 5 lakh he gave one agreement to get sign from me. In that he put advance amount 5 lakh and settlement date was within 50 days but I asked 60 days time then he accepted but he said agreement is just formality to show to my wife. so that I believed him and put signature. He kept with him original copy and said next day will give the xerox copy to me but not given till last. After that bus got accident so I could not arrange the loan so he given 30 more days time. Within that period I arranged the loan amount and balance amount. For receiving loan amount he has to put signature in the ROT Office for name transfer process. He agreed earlier but finally he did not. So I could not settle the amount as he did not put signature. Now he is telling that can not return the advance amount 12lakh. What could I do? Kindly suggest. I have only audio and video evidence.