Explain "late." When exactly did you mail the 2018 return? If it has been in the past several months, it might still be waiting for someone to open it. And...no one can "re-file" it for you. The only way a 2018 return can be filed is by mail. But we do not know if you mailed it in 2019, 2020, or 2021 until you give us some details.
Then be patient. It is taking a very long time for the IRS to process mailed returns.
Per the IRS:
COVID-19 Mail Processing Delays
It’s taking us longer to process mailed documents including:
- Paper tax returns, and
- All tax return related correspondence.
We are processing all mail in the order we received it.
Do not file a second tax return or call the IRS.