What I should do...??

Respected Sir, I (54 year old) am a Farmer and are three brother. I have PAN but my income couldn't cross the basic exemption limit of IT in any F.Y., so I never filed ITR. We sold a piece of agricultural land (on which Capital Gain Tax is not applicable) on 25.04.2010 and found Rs. 27,00,000/- ( 09 lac for each) & 15 lac as cash (not shown in sale deed) as sale value . I have submitted cheque for Rs 09 lac in my a/c & also deposit Rs 15 lac of cash as that time my brothers not holding any account. After that on 10.04.18 I hv got a notice u/s 148 from income tax office to submit my return within a month. Now my question is that- 1. How to make this money accounted? Which type of ITR should be filed so that I can show this amount is tax free or exempted from IT and obtained through valid source of income? 2. As that time a big mistake done by me was depositing of whole cash amounts in my a/c. 3. Shall I have to declare my all movable and immovable property in my income tax return along with valid source of income. 4. As of now I have not such big amount to pay, what else I should do to overcome this crisis. Plz help me.....!!!!