No one else has access to your account(s) so you will need to look for yourself to see if you have an account from which you prepared and filed a 2018 return. It seems odd that you would be just now hearing from the IRS about 2018. If you owed tax due for 2018 your only proof that you paid would be your own bank or credit card records.
You have to access your own account and/or print it for yourself using exactly the same account and user ID that you used when you prepared the return.
Start a 2023 return online and enter some personal information so that the menu on the left opens up and lets you access your past year returns.
https://ttlc.intuit.com/community/prior-year-return/help/how-do-i-access-my-prior-year-return/01/270...
Many people have multiple TT accounts and forget how to access them. Log out of the account you are in now.
Account Recovery
https://ttlc.intuit.com/questions/1901535-forgot-your-turbotax-online-user-id-or-password
https://ttlc.intuit.com/questions/1901486-how-many-turbotax-accounts-do-i-have
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/1901659-find-your-tax-data-file-in-mac
https://ttlc.intuit.com/turbotax-support/en-us/help-article/tax-return/find-last-year-tax-data-file-...
You can get a free transcript from the IRS or for a fee of $43, an actual copy of your tax return.
https://www.irs.gov/individuals/get-transcript
https://www.irs.gov/pub/irs-pdf/f4506.pdf
**Disclaimer: Every effort has been made to offer the most correct information possible. The poster disclaims any legal responsibility for the accuracy of the information that is contained in this post.**
