If you filed online last year, then
TurboTax Online saves those prior year returns. You'd just need to log into the exact same account you started or filed those prior year returns in to access them. See here
How do I access my prior year (2016) return?
But if you e-filed or started a return in TurboTax CD/Download version, you would have to save the copy to your computer for future reference. TurboTax does not save/store copies online when you used the CD/Download version of the software.
If you no longer have the saved copies of prior year filed returns, the other option you have is to reach out to the IRS to get exact copies or your transcript from the IRS. You can go here
Can I get a copy of my tax return from the IRS? for steps to take to get an exact copy or tax transcript from the IRS.
