If it's a PDF, you should be able to view it. If it's a *.taxYYYY file, you'd have to install the YYYY program year product on your computer to open it. That's why it's a good idea to save both the *.taxYYYY data file and a PDF of your return each year. I actually save the data file and 2 PDFs--one of the return "as filed" and one with the return plus all TurboTax worksheets and extra pages.
If you have an online IRS account, you could look there at a tax return transcript to see if it has the information that might help you.
NOTE: Remember all PDF tax documents and tax data files are very sensitive files, since they contain your personal ID info, financial data, and possibly bank account numbers, etc. Be sure to store them safely and securely to guard against computer theft, hacking, etc.
