I have filled e retrun for the a.y. 2014 -15 and then for a.y 2018-19. But failed to file the itr for ay. 2015-16, 2016-17, 2017-18. How can this be recitified.or shall i wait for the notice

it depends;basically, you should start out by responding to the IRS request to file for the those tax years if you are requested to do so by the IRS. However, there is no way to tell for certain whether they will eventually ask you to file returns for those years or not, but it depends a great deal on what the IRS has on record for you as reported earnings for each of those years.If during those last years you had income from self employment that was not reported on a 1099 form, then the IRS has no knowledge of those earnings, in which case they normally do not ask you to file. If you file your taxes as a single taxpayer, then as long as you do not have income that is more than the standard deduction and one personal allowance allowed for the year, then generally the IRS does not send you a notice to file a return, as you would not owe any taxes.