we can not see your returns or the IRS notice. is the iRS saying you filed but had mistakes or that they have no record at all of you filing.
if no record of filing then:
if you e-filed in each of those years, you should have gotten several e-mails. the first would say submitted or rejected. if not rejected or fixed and resubmitted you should have gotten a second e-mail each year saying accepted. if rejected and you did nothing to fix and resubmit or mail them, then the iRS never got them.
you can contact Turbo Tax support on Monday for help.
if the IRS says there are errors you can contact audit defense though there might be a fee if you did not already purchase it for each year
The Audit Defense service is provided by TaxResources, Inc., also called TaxAudit.com, in partnership with TurboTax. If you paid for Audit Defense and you received an IRS notice, call TaxResources, Inc. at 877-829-9695, or report your IRS notice on their web site at http://intuit.taxaudit.com/. Do not contact the IRS until you have spoken to TaxResources. They may contact the IRS on your behalf.
TurboTax does not receive any information from the IRS or your state after your return was filed, so no one at TurboTax knows about a letter you received from the IRS or the state.
(what the letters from the IRS mean)
I GOT A LETTER FROM THE IRS
I AM BEING AUDITED
If you purchased Audit Defense:
TurboTax has a special phone number for help with IRS/state tax letters, which will be easier than going through regular Customer Support. At the page below, click on the blue button that says "Get Help from TurboTax Support". Then it will ask you what tax year is your letter. Then it will ask you what the letter concerns. Then it will show you the phone number during posted business hours.