If you have not received your 2019 tax refund, you should check the status with the IRS. Here is a link that explains how to do that: Check My Refund Status
When did you file your 2019 return? (Online is only for 2020 now). Did you efile or mail it? The IRS is still processing mailed returns. Who did you get a notice from? Did you have the fees deducted from your Refund?