I filed my 2020 and 2021 tax return with turbo tax but the IRS said they never received them. I would like to know what I need to do about that situation?

[xmasbaby0]

What does it say in your TurboTax account?  Does it say "accepted?"   Or does it say something else like "rejected," "printed" or "ready to mail?"   If it says anything other than accepted, you did not file those returns unless you mailed them yourself.  TurboTax does not mail your tax returns for you.  If you did not file, then you can print the returns and mail them in.   Did you owe federal tax?   If so, you will be subject to late penalties and interest which the IRS will bill you for.   

If you need to mail them, mail each one separately and use a mailing service like certified mail so you will know the IRS received them.   

When you mail a tax return, you need to attach any documents showing tax withheld, such as your W-2’s or any 1099’s. 

[fanfare]

If IRS does not have your 2020 tax return you have to file it on paper via US Mail of FEDEX.

Same for 2021.

@wdcatlin