Derailuer Failier

My mountain bike recently suffered a horrible casualty due to the plague of mud. I was riding up the trail after a thunderstorm the previous night in at least two inches of mud. Suddenly my chain came off the front sprocket and as I was putting it back on I notice something was wrong with the rear derailuer. I soon became aware that it had completely broken off and was soon freewheeling down back to the trail head. Further tragedy ensued as  Specialized refused to put the repair on warranty. However, all has now been resolved and I'm back to riding again, although with the impending evils of school on the horizon, I will soon be confined to only doing so only the weekend.