TurboTax does not support tax year 2011.
If you are unable to locate the software to install on your computer so you can open the 2011 tax data file, then you will need to purchase the software from an online retailer, such as Amazon.
The 2011 tax data file with a file extension of .tax2011 can only be opened by the 2011 TurboTax desktop software installed on your computer.
If you saved a PDF of the 2011 tax return, that PDF can be opened by any PDF compatible application, such as Adobe Reader.
Way to support your own product. If the format you offered to save tax history isn't universal, you should offer a product that views these files. No one saves software from 2011. And, I'd guess, finding a copy now is near impossible. Thanks for nothing.
Even the IRS only saves returns for seven years. You do not say why you are trying to get to a 2011 return.