Many people have multiple TT accounts and forget how to access them.  Log out of the account you are in now.

Account recovery

https://myturbotax.intuit.com/account-recovery/

https://ttlc.intuit.com/questions/1901535-forgot-your-turbotax-online-user-id-or-password

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.

https://ttlc.intuit.com/questions/1901486-how-many-turbotax-accounts-do-i-have

https://ttlc.intuit.com/questions/1901535

https://ttlc.intuit.com/questions/1901659-find-your-tax-data-file-in-mac

https://ttlc.intuit.com/questions/1900721-find-your-tax-data-file-tax-file-in-windows

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

https://ttlc.intuit.com/questions/1900748-how-do-i-get-a-copy-of-a-return-i-filed-this-year-in-turbo...

@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)