Approximately how long has it been, and how did you file? Did you efile your return, or did you print and mail the return?
If you efiled the return, was it accepted by the IRS for processing? If you used Online TurboTax, you can check the efile status at the Tax Home of your account to be sure it was accepted.
Do you learn anything when you use the IRS "Where's My Refund" tool?
https://www.irs.gov/refunds
What message is shown there? Does it say your return is still being processed?
NOTE: If you mailed a paper return, it can take 6 months or longer just to show up in that IRS tool.