Property transferred on seller's name how to get it back ?

R/sir Mara dada ji na noida ma 1987 ma industrial property karide. And sir 2 year ka bad seller ki deeth Ho gyi or Mara dada Ji purchaser abhi bhi jinda ha Mara dada Ji na agreement to sale notry sa registered Karwaya 3rs ka stamp paper par. Paper par witnesses ka signature bhai ha and sir WILL, NOC, SPACIAL POWER OF ATTORNY, is par saller or purchaser ka signature ka only or ya 3 paper notry sa regesterd Nahi ha. Sir Hamara 1987 sa hi kabja ha or saller ki leese deed and property ka orignel paper Hamara pass ha. Or authority ma abhi bhi seller ka name ha sir is case ma property Hamara name Kasa hogi. Or sir seller ka 3 bacha bhi ha Kya Hama unsa koi risk ha or sir hum apna aap ko Kasa majbut kara Thanking for you