If you have filed a 2019 tax return and need to change or add your direct deposit information, the IRS has prepared a portal for you to use. Please see this IRS website Get Your Payment.
Please note, if you can not update your bank account information, then the IRS has already tried to process your payment to you through your old bank account. If this is the case, you will have no choice but to wait until the IRS sends you out a paper check.