You have to access your account(s) using exactly the same account and user ID that were used to prepare the return.
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
If you are asking about a stimulus check--it is too late for one in 2020 if you did not already use the IRS non-filer sire, but you have another chance in 2021