Use this TurboTax account recovery website to get a list of user ID's for an email address. Run the tool against any email addresses you may have used
https://myturbotax.intuit.com/account-recovery/To finish 2015, you have to download the .tax2015 file and open it in the 2015 Desktop program installed on your computer. If you paid for the Online version you can call in and ask for the Desktop program to finish. You have to print and mail prior year returns.
Here's how to finish
https://ttlc.intuit.com/replies/4186197
