I mailed my 2023 federal and state returns. I don't get a refund. how do i get confirmation my returns were received?

The IRS and the state do not send any type of confirmation that the tax returns were received.  Unless you used the US Postal Service to mail them registered or certified, then you would have received confirmation that they were received. 

You do not get a confirmation.   If you used certified mail or some other maIling service with tracking you would know it was received.  If you owe, you will just have to watch your bank or credit card account for the payment to be made to the IRS and/or state.