If you’re asking about e-filing your original 2018 tax return, that can no longer be done. Prior year returns have to be paper-filed, since e-filing is no longer available.
Please see the TurboTax Help article How do I prepare a 2020, 2019, or 2018 tax return? for more information on filing your 2018 return.
You might also see Form 1040 (2018) and Instructions for Form 1040 (2018) for specific guidance.
If this doesn’t answer your question, please post back, and be as detailed as possible.
As DawnC notes above, the law gives taxpayers three years to submit a return and claim a refund.
