Only the TurboTax software for the tax year of the amended return can be used.  So if you need to amend a 2017 tax return, the TurboTax desktop software for 2017 has to be used.

If you completed the 2017 return using the online editions then see this TurboTax support FAQ for amending the tax return - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-turbotax-online-return/01/27371

If you completed the 2017 return using the desktop CD/Download editions then see this TurboTax spport FAQ or amending the tax return - https://ttlc.intuit.com/community/amending/help/how-do-i-amend-my-return-in-the-turbotax-cd-download...

DoninGA - thank you very much for your prompt response. What if I was not able to find the 2017 Turbo Tax CD, is there a way I could find this version to install on my computer?

You can buy 2017 here or check Amazon, etc.

https://turbotax.intuit.com/personal-taxes/past-years-products/2017 

Do you have the data file ending in .tax2017 on your computer?  You will need that to open in the program to amend.

Contact TurboTax support and speak directly with a TurboTax support agent concerning this situation... they may push you a download for free ...

See this TurboTax support FAQ for a contact link and hours of operation -https://ttlc.intuit.com/questions/1899263-what-is-the-turbotax-phone-number
They are available M-F  from 5 a.m. to 5 p.m. Pacific time.