The batteries probably just ran down. The ESC will shut the motor off when that happens. Don't keep rearming it to keep flying longer (unless you get in a bad spot and you have to), that's not good for the batteries.
Most ESCs have a BEC (battery eliminator circuit) that provides power to the receiver and servos. That helps save weight; the motor battery has more than enough extra capacity to power the electronics. Don't hook up the receiver battery and the ESC at the same time (not sure what would happen but I doubt it would be good!)