If you want to use TurboTax to complete and file the 2012 return go to this website to purchase and download one of the 2012 desktop editions - https://turbotax.intuit.com/personal-taxes/past-years-products/

A 2012 return can only be printed and mailed, it cannot be e-filed.

You can also get free federal forms, schedules and instructions for prior tax years from the IRS - https://apps.irs.gov/app/picklist/list/priorFormPublication.html

Note: If filing for a tax refund the time to file a 2012 tax return has expired.  To file a 2012 tax return for a tax refund had to be filed on or before April 15, 2016.