Capital gain calculation

respected sir,

My grand father had land in Usmanabad Maharashtra long ago the same got transferred to me from time to time. I have no valuation paper of the said land & last year the land got acquired by govt. Now my question is how shall i compute capital gains of the same. The govt dept has deducted TDS us 194A (10%) on the consideration. Kindly help me to get the refund of the same as i have already invested the sale consideration in buying residential flat.