Service broker not getting messages when enabled
To answer your questions :


Check default trace to see when it got disabled
when you altered the db with NEW_BROKER, it did more damage than you have thought of 


  If you created any route with service name and service instance then it will become invalid as the route service instance value no longer reflect the destination service_broker_guid. It goes w/o saying that doing NEW_BROKER on a database that does have running conversations that span isntances (or even DBs in the same conversation), these conversations will have one half 'nuked' and the other half will be left stranded, unable to make any progress (will have to be cleaned up with END ... WITH CLEANUP or the other database will also have to be NEW_BROKER-ed).



Unfortunately, your best bet is to re-setup service broker from scratch.