We use our Roku 3 at least twice a week. It doesn't move, we have one TV, and nobody but my husband or I touch it. Attempting to watch a movie last week, our TV couldn't acknowledge that our Roku was even there. We had to reset and enter all of our channels and passwords in again. After watching our movie, we turned our TV off. The next night, we went to watch something else and the Roku was again invisible from the HDMI port that it is hooked up to and again, and we had to perform the same actions. This is getting annoying. What is going on?
The issue could be a loose, bad or even just an old HDMI cord. Try a new one as Rokus tend to be a bit more sensitive to old or cheap HDMI cords than some other devices.
I had to replace my HDMI cable for my Roku 3 a few years ago. That old "bad for Roku" HDMI cable has been working fine with my DVD player.
TheTick (aka "Moose Twit" affectionately called by chht) Roku 3 for Pokémon TV / YouTube / Animal Planet GO / HBO GO. Chromecast for most other media because Roku Mirroring sucks , how many clicks in Wndows 10 (about a dozen) to Miracast on Roku vs 2 with Chromecast. Verizon FIOS TV and Internet Service