The aircraft would yaw in the direction of the non-working engine side due to asymmetric thrust, with possible autopilot disconnect. Rudder, and then trim would be required to hold the desired track, and the autothrottle would be disconnected by the pilot, with power applied to the good engine. I believe in a 777, the application of yaw is also automatic (but not in older aircraft, like a 737/757, where it is all manual). If the loss of thrust was for any length of time, and at high altitude, the aircraft would need to descend.