I need to amend my 2019 return. This isn't an option in "Your tax returns and documents" and when I ask "help" the instructions given do not match what I can access.

TurboTax no longer provides nor supports 2q019 software.  It is too late to amend a 2019 return to get a better refund.

If you need to find a copy of your 2019 return you can find it in the account you used to prepare it, but you cannot use TT to amend it.

  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.

 https://myturbotax.intuit.com/

Start a 2024 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/01/27010

https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/save-2021-turbotax-online-return-pdf/L8dHfRkpT_US_en_US?uid=m5y4ch1y

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

https://ttlc.intuit.com/turbotax-support/en-us/help-article/account-management/many-intuit-accounts-turbotax/L9aVfKS1Z_US_en_US?uid=ll5g6zcx

Account Recovery

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/turbotax-support/en-us/help-article/tax-return/find-last-year-tax-data-file-tax-file-computer/L0XJvPaJr_US_en_US?uid=m6gufxei

https://ttlc.intuit.com/turbotax-support/en-us/help-article/data-systems/find-tax-data-file-mac/L4VNGm33S_US_en_US?uid=m6guhab0

You can get a free transcript from the IRS or for a fee of $30, an actual copy of your tax return.

https://www.irs.gov/individuals/get-transcript

https://www.irs.gov/pub/irs-pdf/f4506.pdf

SAVE YOUR TAX RETURNS !

EVERY year before mid-October you should save a copy of your tax return as a pdf and print a copy of it for your records.  That way you will not be searching online frantically when you need it for a lender, FAFSA forms, your next tax return, etc. 

https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/save-2021-turbotax-online-return-pdf/L8dHfRkpT_US_en_US?uid=m6guj526

In order to transfer a past year return to the new return you need the tax file

https://ttlc.intuit.com/turbotax-support/en-us/help-article/import-export-data-files/save-turbotax-online-return-tax-data-file/L4xwOG3LF_US_en_US?uid=m6guk3xl

NOTE:  TurboTax and the IRS save returns for seven years.  Returns older than seven years are purged.

As xmasbaby0 states, you are unable to file an amended return for 2019 through TurboTax. If you are amending your 2019 tax return to claim a refund the time allowed has passed 

The IRS allows you to file an amended return to claim a refund within the later of three years from the filing deadline (April 15, 2020 for your 2019 return) or two years from the date you paid the tax due for 2019.

You are outside of that window and can't claim a refund by amending your return.

You can file an amended return for 2019 to report a mistake that results in a tax liability (for example income that you failed to report in 2019). You will have to file a paper Form 1040X if this is the case.

You can use this IRS tool to determine if you should amend for 2019, click here and select begin to enter your information.

Click here for additional information on Amending Your Tax Return.