You have to sign onto your 2016 online account using the exact same user ID you used to create the account.

Close all TurboTax windows on your web browser (including this one).  Copy and paste the account recovery website link onto a new web browser window and run the tool.

Use this TurboTax account recovery website to get a list of all the user ID's for an email address.  Run the tool against any email addresses you may have used - https://myturbotax.intuit.com/account-recovery

If none of the user ID's received will access your 2016 account, then use the option shown in blue on the account recovery website, "Try something else"

If you used the desktop CD/Download editions installed on your computer, the only copy of your tax data file and any PDF's will be on the computer where the return was created.  TurboTax does not store online any returns completed using the desktop editions.

To access your prior year tax returns sign onto the TurboTax website with the userID you used to create the account - https://myturbotax.intuit.com/

Scroll down to the bottom of the screen and on the section Your tax returns & documents click on Show. 

See this TurboTax support FAQ for completing a prior year tax return started with the online editions - https://ttlc.intuit.com/questions/2559403-how-do-i-finish-a-prior-year-return-that-i-started-in-turb...

If you paid for one of the 2016 online editions of either Plus, Deluxe, Premier or Self-Employed then you will need to contact TurboTax support so they can push a 2016 desktop installation file to your download account.

See this TurboTax support FAQ for a contact link and hours of operation - https://ttlc.intuit.com/questions/3401489

Submit your question/problem during business hours and then use the option for Call (a phone number will be provided for Call) to speak directly with a TurboTax agent -

Note:  The Call option will not be available when TurboTax Support is closed.

Support can also be reached by messaging them on these pages https://www.facebook.com/turbotax/ and https://twitter.com/TeamTurboTax