That's common to end up with multiple accounts. First LOG OUT of whatever TurboTax account you're logged into right now. Then 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/
If you used the Desktop CD/Download program then the only copy is on your computer and not saved or stored online.
Do you need it to efile 2018? If you filed 2017 late in the year try using 0 for the AGI to efile.
How to find your AGI
https://ttlc.intuit.com/community/agi/help/how-do-i-find-last-year-s-agi/00/25947
But if your 2017 return didn't get filed or rejected then use 0 for the AGI.
