Hopefully you have not fried the motor. To free a stuck motor: try to reach past the strainer to the impeller and turn it. If you can't do that, remove the electric end cover and find a double flat for a wrench where the shaft goes into the motor. Or maybe you can remove the spring thing from the end of the motor and move the shaft with a pair of vise grips or pliers. Don't damage the place where the spring thing mounts. Don't try to move the motor with the plastic fan thing near the pump, you'll just break it, and then you really have problems.
To keep a motor from sticking, thru off season occasionaly spin the pump, just a few seconds will do, don't need water.