Most users experiencing this issue have more than one TurboTax account and don't realize it. In order to access a return you've filed in TurboTax Online, you must use the EXACT account (same username and password) that you used when filing. See the TurboTax FAQ below for instructions on how to proceed.
"Why can't I find my return in Tax Home or My Docs?"
https://ttlc.intuit.com/replies/3290682
*** I am NOT a tax expert. I am a seasoned TurboTax user, and volunteer to provide assistance to TT users. Nothing I post is to be considered TAX ADVICE; I bear no legal liability for responses.***