Need legal advice

I had purchased a property (land 100 Sq Yd in Complate Consrucation) from the GPA Registered from of vendor before 2 years.

Now the some body told me Vendor  sold the same property to some one else.

I have leaving in this properity since 3 years I have proper proof on my name

1. Electricity Connection on this properity

2. Bank Account

3.Gas Connection

4. House Tax receipts on this Address

5. Ration Card

6.Smart Card

7. Voter I card 

 I had constructed houses worth 35 lakhs. 

Now, in this situation suppose if i loose the case in the worst condition. 

can i claim the worth of the constructed house.