Use the Roku mobile app on your phone
Connect your phone to the same Wi-Fi network the Roku was previously using
Open the Roku app and sign in if needed
Select your Roku device in the app
Go to Remote in the app
Use the app remote to open Roku Settings
Go to Network
Select Set up connection
Choose Wireless
Select your Wi-Fi network
Enter the Wi-Fi password
Wait for Roku to connect
If the Roku is not on the same Wi-Fi network, use a mobile hotspot with the same network name and password as the old Wi-Fi
Connect the Roku to that hotspot
Use the Roku app remote to change the Wi-Fi settings
Switch the Roku to the new Wi-Fi network
Turn off the hotspot after the Roku connects
If your Roku has an Ethernet port, connect it to a router with an Ethernet cable
Use the Roku app remote to change the wireless network settings
Disconnect Ethernet after Wi-Fi is set up
If needed, use a universal remote compatible with Roku
Navigate to Network settings
Connect to the new Wi-Fi network
If none of these work, perform a factory reset using the reset button on the Roku device
Set it up again with the Roku app or a compatible remote