Recovery of Original Agreement of sale + Flat + Mumbai

Dear All, Need your advise on below. I sold my flat with Agreement of sale , handed over my original agreement of sale to party so that he can deposit in bank & get loan disbursement. Documents handed over to party after receiving 20% of consideration value payment & enter in to new Agreement of sale . Later on couple of days , buyer came and saying he lost my original papers of agreement of sale (not his) and bank did not disbursed payment . During this time frame , as mentioned in new agreement of sale , i think it will become void as terms of agreement toward payment is not made as agreed. Pl help me to know below. 1. After passing period of payment & non-payment clause mentioned , does this new agreement becomes void automatically or do i need to follow any process to make / record it void with registrar. 2. In this case can i recover my agreement of sale from registration office , what process i have to follow ( I am first buyer from builder) 3. Agreement of sale which was become void recently, will that cause any problem in recovery or during any future deal. pl help.