I filed my 2019 tax returns through TurboTax and show it was accepted, but IRS sent me letter CP80 saying they never received it. Can TurboTax refile?

No.    It is not possible to e-file a 2019 return.   It has to be printed, signed and mailed.  E-filing closed permanently for 2019 returns in October of 2020.

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.  Use a mailing service that will track it, such as UPS or certified mail so you will know the IRS/state received the return.

Federal and state returns must be in separate envelopes and they are mailed to different addresses.  Read the mailing instructions that print with your tax return carefully so you mail them to the right addresses.