Does the IRS say they mailed a check to you? Did you choose to have a check issued instead of a direct deposit?
https://www.irs.gov/forms-pubs/about-form-3911-taxpayer-statement-regarding-refund
https://www.irs.gov/forms-pubs/about-form-3911
https://www.irs.gov/faqs/irs-procedures/refund-inquiries/refund-inquiries-0
Or----did you choose to pay your TurboTax fees by having them deducted from your federal refund? Did your direct deposit not post to your account? If so, the problem could be with the third party bank that handles refund processing.
What is Refund Processing Service?
Santa Barbara Tax Products Group, LLC (SBTPG) is the bank that handles the Refund Processing Service when you choose to have your TurboTax fees deducted from your refund. This option also has an additional charge from the bank that processes the transaction.
You can contact them SBTPG, toll-free, at 1-877-908-7228 or go to their secure website www.sbtpg.com
How can I see my TurboTax fees?