Money paid to broker who died, how to recover the amount paid

I paid advance payment for land purchase to real estate broker, but not land registered, she gave agreement document, suddenly the broker met accident and died, she is single owner proprietor, how can I claim money? Same Situation suffered many people, how can we handled this case, she introduce many land layout, we checked that layout owner, they are not response. We don't know how can we claim money? Please help us.