Thanks for your first post in the Roku Community!
We appreciate you letting us know about the issue with the Roku mobile app that is not finding your Roku device. We would like to know what went wrong so we can assist you further and fix the issue.
As a first step, we recommend making sure to use the Roku mobile app to connect to your Roku device, you must connect your mobile device to the same wireless network.
If your Roku device does not appear on the discovery screen, learn why the Roku mobile app may not be able to find your Roku device.
If the steps provided by the Support page still aren't helping, please reply back and we will be able to assist you further.