I had filed my refund last year but I never got the check, what do I do?

assuming you e-filed 6 or months ago and got an acceptance e-mail you can put through a lost check trace.  the IRS is still working through mailed in returns. probably has millions yet to process. so if you mailed it in lately, you'll have to wait some more until the IRS, hopefully, announces it's processed all those returns.

https://www.irs.gov/faqs/irs-procedures/refund-inquiries/refund-inquiries-0  

 Did you efile or mail your return?  When?  They didn't start opening the mail until June that's been 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?