It is now too late to file an extension thru the TT system and only those out of the country or active military stationed overseas can apply for an extension by mail at this late date.
All you can do now is simply file the return. If you have a refund coming the extension is totally unneeded.
Log in using the same userID to continue 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://myturbotax.intuit.com/account-recovery/
https://ttlc.intuit.com/questions/1901535-forgot-your-turbotax-online-user-id-or-password
