lost the property documents, no xerox available, how to register it

My father bought a land eight years ago and got the first document 'daleel' but the registration was pending for many years due to some reasons then he finally got time to do the registration so he hired a family lawyer and he gave him that only document to the lawyer without keeping a xerox of the same. A year later that lawyer died of cancer and the documemt was no where to be found . now we have no document with us to prove anything and do the registration. We also asked the seller to complete the registration but they do not cooperate with us. So can we take action against the seller without any document since they do not cooperate . p.s we have not told them this secret.