My bank account is closed down, but I didn’t know this until after I had e-filed. How can I get my tax return sent to another bank account?

You cannot change it after you filed.   If the deposit is refused the IRS will mail a check to the address on the tax return in about 3 weeks.

If your bank account is closed, the bank will reject the direct deposit.  The IRS will then mail you a paper to the address on your tax return.