My 5 year old played with the Roku remote while we were not looking, and now my Roku screen is black and white. Normal TV is OK, and the TV control menu is in color - the black and white screen is limited to Roku only. We read some of the community posts and followed advice - switched up the HDMI cables, performed a soft, then factor reset, and nothing has restored the color. I've seen similar posts recently, but not replies...is there a solution out there??
I cannot tell if you have a Roku player/stick, or a Roku TV - however, assuming its a player/stick, its possible that the Color setting for the specific HDMI port was reduced to 0 (zero), which would in fact create the appearance of Black & White (each input/mode of most TVs have their own individual settings, including Color).
(E.g. If I reduce the Color setting to 0 on my TV's HDMI 4 port (that I have a 2019 SS+ connected to), all of the Roku's output is in B&W)
So, check the TV's color setting, make sure it hasn't accidentally been set to 0 for the input/port/mode of the Roku.