As per your query it is clear that you need information regarding the owner of the plot which you intend to purchase.
Since the municipal corporation is not in a position to provide you the details of the owner the only way left with you is to file an RTI (Right To Information) and seek information regarding the owner of the plot which you intend to purchase.
The first step to file an RTI with a department of the central government would be to identify from which department the information has to be obtained. For instance, anything related to income tax should go to Income Tax department or defense related query should go to Ministry of Defense.
The next step would be writing your RTI application in the prescribed format. Also, this format isn’t mandatory and you can submit your application on a plain paper as well. The language of the application can be Hindi or English. Similarly, the government can also respond in either language.
Make sure that the questions you ask relate to only one subject; the application has a chance of rejection if you ask more than one questions in a single RTI Application. For instance, if you are enquiring about your passports, then ask questions which are only related to the passports.
As you might know, there is some amount charged for each RTI you file. Thus, to file an application to a central government department, attach application fee of Rs. 10/- in the form of Indian Postal Order.
Once all the above mentioned steps are completed, send your RTI application via speed post/registered post and wait for the government’s response. If you don’t get a reply within 30 days of sending the application, you can approach the central information commission.
Unless and until you do not have the information about the owner of the plot you cannot buy the plot.
Hope it helps!
Regards,
Anusha Singh