What files do you have on your computer? Like the pdf file or tax file ending in .tax2015? As the post above says you can no longer download the 2015 program to open your return.. Or did you use the Online version?
You can request a transcript from the IRS
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
https://www.irs.gov/pub/irs-pdf/f4506.pdf
