Help & troubleshooting for channels on your Roku device, including adding/removing channels, logging in to, authenticating, or activating a channel, channel-specific playback issues, assistance contacting channel publishers to report issues, and adjusting channel-specific settings.
Re: What happened to Facebook, I had it now there's no app
If it was a public channel in their store, it appears it has been removed. If it was a private channel, it's possible that Facebook didn't support it and asked Roku to remove it. whichever case it was, it's no longer available.
Dan Roku Stick (3600), Ultra (4640), Premiere (3920), Insignia 720p Roku TV, Sharp 4K Roku TV, Nvidia Shield, Windows 10 Pro x64 running Serviio and Plex on a wired Gigabit network.