How to dissmis recovery suit

Recovery suit filed by ptff on ground of signature made by def on blank unregistered bond paper of 100 Rs which was given by def to ptff as security for confirm purchase of flat for which deff was made agreement of sale. After delay of near about six month deff was purchased flat from ptff with registerd sale deed by giving 9lac with installment by check and remaining with loan. Also def forget to demand his blank 100 Rs bond.After 2 year ptff filed recovery suit against def stating that 2lac given by def through one check which is already mentioned in sale deed was given to him as hand loan by def and he returned that hand loan by cash and that transction is made on 100 Rs bond which was given as security for completion of sale deed. So now he demanding 2lac Rs which is given by def for purchase of flat. There was no any transction happen between them regarding hand loan. Even ptff has added witness name and sign on that bond paper which are unknown to def. So as I am def council please guide me whether it is possible to dismiss the suit or how should I proceed further? It is better for def to add parties to suit which r witness for register sale deed?