Suddenly will not play Radio 2

Just to confirm you are trying to play this via the Sounds Sonos plug in?

Works for me (S2 system).

Note that all Sonos does is point their speakers to a BBC server, they don’t host the content themselves. 

It’s frustrating when a station that was working normally suddenly stops playing. It may be worth checking the Sonos app, updating the system, and confirming whether the issue is only affecting Radio 2 or other stations as well. Hopefully a quick refresh or service update resolves it.