Property sale issue

Hi sir, Nice to meet u. My name is sreenivasula reddy and i am from bangalore. I had a dought regarding one of my civil issue.In the year 2014 January moth my father had given an amount of 20 lacks to one of my relative through land sale agreement with 200 rs value bond papers. This agreement is passed through two of witnesses at the time of effective. After one and half years land seller is not willing to register his land and not paying my fathers 20 lacks. Then immediately my father filed a civil suite on the seller in December-2015. Now the suite is being running since 9 months. Three months back land seller has replied to my father's notice, stating that the agreement is a fake one and he dint took single rupee also from my father. And the signature that he has made on the agreement is a fake signature. But we have an other agreement which he has made with other party for some land sale. So the other agreement has registered also. When we compared these signatures, we can understand that the signature where he signed on my agreement is absolutely original. And both witnesses also agreeing that he has taken 20 lacks in presence of them.