TurboTax does not support tax year 2011.
If you are filing the 2011 return for a tax refund, it is to late to file. A 2011 return with a tax refund had to be filed on or before April 15, 2015.
You may be able to purchase the 2011 software from an online retailer, such as Amazon. However, there is no guarantee that you will able to get any updates for the software or be able to download a state tax program.