If your 2016 return was prepared using desktop software installed on your own computer, that is where the files were stored. They are not stored online with TurboTax. If you did not back up on a flashdrive, etc., or save a hard copy then you can get a free transcript of your return from the IRS or for a fee of $50 an actual copy.
https://www.irs.gov/individuals/get-transcript
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