I will suggest you first for Legal Proceedings, and then in general advice you as:
So firstly You are saying that:
" I have spended nearly 12 lacs for the house. I have proofs and taken house loan for the same for Rs. 5 lacs".
"How I can get my money back or by paying land value "
So You are having all the 'documentary proof' surely you can initiate legal proceedings on the basis of that documents, becuase you obtianed loan for the costruction of house on your name, the same is in bank records and having supporting documents. So by submitting all the documents of loan process and construction expenditure receipts and land documents you can file a civil suit get back money.
Secondly in general:
Against whom you want to initiate legal proceedings....he is your "FATHER".....due to him only you are now at the this stage.....a "TAX ANALYSIST"......think how much amount he spent for you since your birth to till you become a standing person...... did your father demanded with you at any time by saying that since your birth I spent so and so money/time/love towards you since birth and now give me back the same, as you are now at this stage and can repay ..........I think he didn't......am I right.........as per me we as a human being can't calculate and count the same in money.......but now you as a son and more over a Tax Anlysist who is in a good position ...but only for few "Lakhs of amount " want to initiate legal proceedings..
Sorry to say Dear Manjesh Poojary.....
on the face of facts as stated by you it is showing that........suppose if your father demand with you, to give me back the money which I spent for you since birth to till this stage........on such demand of him you will ask with him " what is the documentary proof you are having to show that you spent so and so money for me" .....????? ...... am I right.....
So Mr. Poojary, he is your father, be patience, he won't give that land to others except you, becuase you are his son. In urdu/Hind there is a saying " Sabar ka Phal Meetha Huta hai".
So wait for some time, don't fight with your father only for a piece of land.