Cheque bounce

Hello im P.venkatesh . I need a help regarding my cheque bounce issue..i had given blank cheque for the security of a 1 lakh chit of twenty months which was organised by a local person who was residing in my hometown.i had paying monthly chit amount to the organising person up to date ..but suddenly he had a loss by some other persons who participated in the chit which i am ..so my due of amount to be paid was 4 months ...so suddenly the whichever person conducting the chits he left the city with all money who all r in the chits ...so after a few days i got a notice from the court which ive given a blank cheque to the organiser ...he had filled a case from an another person dat i dont knew ...the total amount he had filed was for 3 lacks ..but actually the amout i shud pay was 25000....so im going the court and i had replied a notice from my advocate ..the cross examination is going to start for my next session ..so i want an help how to prove dat the person who filed the case whom i dont know ..and help me how to win the case really i cant pay any dat much of amount .......so please help sir thanking you