Do you only have a file ending in .tax2016? You don't have the pdf file? Sorry you can’t update old Desktop programs to download the state program so you can’t open that file.
If you have an old .tax file and can’t open it, You could try the TaxPrinter service to convert a .tax file to pdf at
http://www.taxprinter.com
They might be expensive and it is probably not safe to email tax returns back and forth. They are not related to Turbo Tax.
Or did you use the Online version?