Hopefully you saved a PDF of the return you can open with any PDF reader. If you only saved the .taxfile then you will need the correlating TT program to open it so you will need to reinstall the program.
The tag below your question indicates that you are using TurboTax Online. If that's true, see the following FAQ for instructions to view a PDF of your tax return for a prior year.
How do I view, download, or print a prior-year tax return?
If you used the CD/Download TurboTax software for the year that you want to view, and you have the .tax20yy file, the only way to view the file is with the CD/Download TurboTax software for the corresponding year. If you purchased the software as a download from TurboTax.com, you can download it again and reinstall it.
If you are unable to reinstall the software you could try TaxPrinter. You send them your .tax20yy file and they send you back a PDF of the tax return, which you can then print with Acrobat Reader. TaxPrinter has no connection with TurboTax. I have never used TaxPrinter, so I cannot make a recommendation. I'm just making you aware of it.
If you have a .tax or .tax20xx file you need that year's Desktop program installed to open it.
Turbo Tax doesn't have programs older than 3 years. You might be able to find one on Ebay or Amazon or somewhere but you wouldn't be able to update it or download the state program.
You could try the TaxPrinter service (not connected with Turbo Tax) to convert a .tax file to pdf at
They might be expensive and it is probably not safe to email tax returns back and forth.
OR get a copy from the IRS -