How did you choose to receive your refund? If you haven't already, please download and/or print a copy of your completed return. Next, confirm the refund method you chose. You can find this information beginning on line 20a of your 1040 form.
If you chose direct deposit, verify that you entered the correct routing and account numbers. An error can cause your refund to get sent back to the IRS. In this case, they will mail a paper check to the address they have on file for you.
Source: What if I entered the wrong bank account for direct deposit?