Many people have been complaining about this problem but I think you are the first to say that all channels are unavailable. There's a thread here http://forums.comcast.com/t5/XfinityTV-Website/ABC-is-not-a-part-of-your-subscriptions/td-p/1989101 where one of the Comcast people has replied to people having this problem, you should post there or you can private message ComcastDaniel who's been helping people with this.
- Norm