Many people have multiple TT accounts and forget how to access them. Log out of the account you are in now.
Or did you use the desktop version of TurboTax? If so, the files are on your own hard drive or any backup device you used like a flash drive.
To get a copy of your previously filed returns prepared with online TurboTax https://ttlc.intuit.com/questions/1900748-how-do-i-get-a-copy-of-a-return-i-filed-in-turbotax-online
@taurusd74 I hate having to ask---but when did you prepare the 2018 return? Was it prepared and e-filed or mailed before the filing deadline in 2019? Or prepared --printed, signed and mailed ---using 2018 desktop software?
If you used the most recent online software and put 2018 income on the return--that was incorrect. Online was only for 2019 returns. I am wondering if that is why you are having trouble looking for it. If you used online software in 2020 you did not prepare a 2018 return. (You prepared a 2019 return--which is all that will show up in a TT account)