More words describing the situation would help. One possible interpretation is that you have connected a very old Roku to an even older TV. (ie: stuff from before the world went to HDMI) That old stuff used 3 or 5 wires to connect a device to a TV and each had to be connected and to the correct ports. Or you might have a not-so-old Roku connected to some conversion device. Or possibly neither guess is correct.
... or maybe ...
We really do need more information from you before we can begin to try to help.