To access your current or prior year online tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. Click on the Year and Click on Download/print return (PDF)
You can also get free transcripts of your federal return from the IRS - http://www.irs.gov/Individuals/Get-Transcript
See this TurboTax support FAQ for upgrading to Plus - https://ttlc.intuit.com/questions/2586262-how-do-i-purchase-turbotax-plus-so-i-can-get-my-tax-file
Or -
If you have filed the 2017 tax return and need to upgrade and purchase Plus then use this procedure if the TurboTax support FAQ procedure is not working for you -
To upgrade to Plus after you have filed so you can access your prior year tax returns -
Access your current online tax return sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/
Scroll down and Click on Add a state
On the left side of the screen click on Upgrade. Scroll down and select PLUS More Help & Tools. Click on Upgrade Now (if Plus is grayed out then you are already using Plus and only need to pay for the upgrade)
To pay the TurboTax online account fees by credit card so you can access your prior year online tax returns, click on Tax Tools on the left side of the online program screen. Then click on Print Center. Then click on Print, save or preview this year's return. On the next page, to pay by credit card, click Pay Now. On the next screen just click on the Continue button. The next screen will show a review of your Fees, click on Continue. Complete the next screen to pay by credit card and click Continue.
