If you’re saying that in a prior year your Earned Income Credit (EIC) was disallowed or reduced for something other than a math or clerical error, and you failed to file the form to receive EIC again with the return you’ve just filed, you’ll need to amend your return to file Form 8862.
Please see the TurboTax Help article "How to amend (change or correct) a return you already filed" for instruction on how to amend your previously-filed tax return.
For guidance in entering Form 8862 into TurboTax, please see TurboTax article "How do I enter Form 8862?".
If this is not the issue you’ve encountered, please provide additional information.