Hi Subhasis,
Cash deposit more than 10 lakhs in S.B. account is always - a waiting invitation for scrutiny. Since the assessee has not filed his returns, your first action should be to file a return (ITR 2 or preferably 4) by getting your working of (hopefully) capital gain tax done by a CA or tax consultant. The returns will be considered belated as it is time barred.(subject to penalty). Give a copy of the acknowledgment to the officer.
During scrutiny, let officer go through the working of taxation and decide the course of action. Kindly take proper guidance of a qualifed consultant before filing returns as capital gain is a vexed section. Filing ITR - 1 (sahaj) is a simpler process and most of your working is done by your employer. Please don t mind, but if you can afford a consultant, you should always have one in handy as he will save you tax in comparision to how much you pay him/her in fees.
All the best.