To the regular Turbo Tax Online version or the CD/Download Desktop program?
For Online Turbo Tax you have to start over with a new account and enter everything again. Start a new Online return here, https://turbotax.intuit.com/personal-taxes/online/
For the Desktop program you might be able to download the .tax2018 file and open it in the Desktop program. See if you can save your return as a tax data file ending in .tax2018. Do you want to buy the Desktop program?