My Roku tv remote quit working with the Roku remote.

If it's still under warranty, onn should replace the remote.  If it's not, you can get the Roku simple TV remote or a voice remote.  Many universal remotes also support Roku TVs.

Where can I get support for my Roku TV™? | Official Roku Support

Roku remotes can be purchased in some stores or directly from Roku:

Accessories | Roku Player, Streaming Stick, Smart TV & Audio Accessories | Roku