If your prior returns are locked then you must upgrade to PLUS & pay for the PLUS upgrade to unlock them... however this can ONLY be done when the ONLINE system is operational. Right now the system is down while it gets transitioned to the 2019 version ... this blackout period happens every year. The 2019 online program will be operational sometime in December.
Access to prior year returns
https://ttlc.intuit.com/questions/3355524-when-does-access-to-my-prior-year-turbotax-online-returns-...
https://ttlc.intuit.com/questions/3404575-how-do-i-access-my-prior-year-2017-return
You can get a free transcript from the IRS:
https://www.irs.gov/individuals/get-transcript
How do I get a copy of a return I filed using online TurboTax?
https://ttlc.intuit.com/questions/1900748
How do I get a copy of a return I prepared using desktop TurboTax?
https://ttlc.intuit.com/questions/1900639
Note: Every year, before mid-October, print a copy of your current year tax return and save it as a tax file and pdf, too. That way you will have it when you need it for school, a loan, next year’s tax return, etc. without going through a lot of aggravation (and expense) to get it.
https://ttlc.intuit.com/questions/1899645-how-do-i-save-my-2018-turbotax-online-return-as-a-tax-data...
https://ttlc.intuit.com/questions/1912544-how-do-i-save-my-2018-turbotax-online-return-as-a-pdf
