What is the model name and number of this Roku? (Roku menu path Settings > System > About will show you)
If this is an older Roku model connected to your tv via red, white, and yellow plugs, be sure they are plugged into the correct jacks on the tv. The red and white plugs carry the stereo audio information so plug them into the red and white audio input jacks. Plug the yellow one into the yellow component video jack if the tv has one.
If your tv does not have a yellow composite video jack, some tvs have combined composite and component video into a single set of jacks and have circuitry that can tell which is connected. On such sets, plug the yellow plug into the green component jack - the red and blue component jacks may result in a monochrome display. And be sure the red audio line is plugged into the red audio input jack, not into the red component video jack.
Roku Community Streaming Expert I am not a Roku employee, only a user like you. Please, no support questions via private message -- post them publicly to the Community where others may benefit as well. If this post solves your problem please help others find this answer by clicking "Accept as Solution.".
Streaming Stick 4K+ 3821 | Streaming Stick+ 3810 | TCL Roku TV 43S245/C107X