Both TurboTax and the IRS only retain tax returns for the past seven years, so the 2012 tax return or transcript may not be available.
To access your prior year online tax returns sign onto the TurboTax website with the User ID 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 the Year and Click on Download/print return (PDF)
If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created. TurboTax does not store online any returns completed using the desktop editions.
Or go to this IRS website for free federal tax return transcripts - https://www.irs.gov/individuals/get-transcript
For a fee of $43 you can get a complete federal tax return from the IRS by completing Form 4506 - http://www.irs.gov/pub/irs-pdf/f4506.pdf
Do you want a transcript or a copy of the tax return? They are two different things. "Transcript" has a special meaning in relation to a tax return. A transcript is a document you get from the IRS that lists information from your tax return, but not in the format of the actual forms. A copy is a copy or image of the actual tax forms.
DoninGA gave you instructions for getting either a transcript or a copy. Be clear about which one you want.