Are you using online TurboTax or the CD/download?
If you are using online, you need to use exactly the same account and user ID that you used when you began working on the return.
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.
**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.**