I was told by my bank that my tax refund was sent back to the IRS

if you want to find out why call them back?  could be because of a bad account number or the names didn't match.

If you e-filed:

Banking information for direct deposit is wrong

If you entered incorrect banking information for your refund, you can change it if your return is rejected.  If it is accepted, however, it is too late to change it.  The bank will reject the refund and send it back to the IRS.  Then the IRS will issue a paper check and mail it to the address you put on your tax return.  Expect a delay of at least a couple of weeks to receive your refund.

Here is what the IRS says about entering incorrect banking information

https://www.irs.gov/help-resources/tools-faqs/faqs-for-individuals/frequently-asked-tax-questions-answers/irs-procedures/refund-inquiries/refund-inquiries-18