I never got my 2019 tax return

Do you mean your tax refund? If so, please contact the IRS below, because it is the IRS that processes and issues refunds.

How do I contact the Internal Revenue Service (IRS...

Do you mean your Refund? Did you efile or mail your return? When? They didn't start opening the mail until June that was stacking up. Back in March the IRS closed their processing centers and stopped processing mailed tax returns.
See this IRS page for the latest information
https://www.irs.gov/newsroom/irs-operations-during-covid-19-mission-critical-functions-continue

If you efiled....Was your return Accepted?When you efile you get back 2 emails. The first email only confirms the transmission. The second email says if the IRS (or state) Accepted or Rejected your efile.

Then only the IRS can tell you. IRS Where's my refund https://www.irs.gov/refunds/
Make sure you are using the refund amount from your actual federal tax return and not the combined amount Turbo Tax showed you at the end. That was for federal and state combined.

When you log into your account you should also see the status and if it was Accepted or Rejected, Started, Printed, Ready to Mail, etc.  what does it say?