If it's just ice, you can probably work some grease into it. Check the rubber boot at the end, is it torn? Disconnect the cable from the caliper. You should be able to slide the cable in & out to see if it's smooth.

If it's rusted I guess I'd replace it. How much time are you willing to spend instead of buying the cable.

If the cable was stuck, the wear on the rotor was a result of the brakes dragging.