You can't do a prior year return online or efile it, but you can buy the Desktop Download versions for 2012-2014 from Turbo Tax here. Be sure to pick the right one, Windows or Mac....
http://turbotax.intuit.com/personal-taxes/past-years-products.jsp Or you can check for Turbo Tax for all years on Ebay or Amazon, etc.
Either way you will have to mail in your return. And if you are doing more than 1 year, send each year in a separate envelope. Sometimes the IRS will just staple all the sheets together and miss a second return.
Or if you have a simple return you can get the blank forms from the IRS and fill them in by hand for free
