My father now aged 65 years, had purchased the agricultural land in Gurgaon area (Farukh Nagar) in 1987. He sold this land in 2011 at Government circle rate. The money was received by demand draft. He has not filed any income tax return. Please advice if the amount he got by selling that land is taxable or not?
In short Yes, your father needs to pay tax. Please consult a CA so that he can advice you better.
In your father's case at the time of purchase it was agricultural land. However at the time of sale, it seems it was Urban, N.A. Land. A C.A. would advice you the exact exemptions and gains.
If it was agricultural land at the time of selling, the Section 54B: "Exemption from Capital Gains on transfer of Agricultural Lands in certain cases" would be applicable if your Dad was doing agricultural activity on this land, and after selling has purchased a similar land.