To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show.  Click on 2016

What is the status of the state tax return?  If the status is anything but Accepted then the state tax return was not e-filed.  If you did not print and mail the 2016 state return then it was never filed.

Click on Download/print return (PDF)

A 2016 tax return can only be printed and mailed, it cannot be e-filed.

Print, sign, date and mail the tax return to the State.  Include with the mailed return any forms W-2 and 1099 which have taxes withheld.  Go to this Minnesota website for the address for mailing and what must be included with the state tax return - https://www.revenue.state.mn.us/filing-paper-income-tax-return

There are no penalties for filing a tax return after the due date if filing for a tax refund or there are no taxes owed.

No one else can access your account or your tax returns.  Look at your account for 2016--does it show that your 2016 state return was "accepted" "rejected" "ready to mail" or "Printed?"  If it shows anything other than accepted, then it was not filed unless you put it in an envelope and took it to a mailbox.

And is the state saying you did not file -- or that you did not PAY your tax due?  Only your own bank/credit card records would prove that you paid tax due.  A state tax due cannot be paid from a federal refund.

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   

https://ttlc.intuit.com/questions/3605673-i-got-a-letter-or-notice-from-the-irs

I AM BEING AUDITED

If you purchased Audit Defense:

https://ttlc.intuit.com/questions/2924451-i-bought-max-or-audit-defense-and-now-i-m-being-audited

AUDIT SUPPORT

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.

https://support.turbotax.intuit.com/irs-notice/audit-support/