Please take a strong magnetic magnet on the original magnet in a straight single trip (that is, can not rub back and forth) friction. In general, magnetism can be restored in dozens of cases.
A more complicated method is to use a coil to magnetize a magnet. Or reheat and place in a magnetic field, the magnetic field can be obtained using electromagnetic, do not remove the magnetic field before cooling to the Curie point, after cooling can restore the magnetic field.
The magnet is not magnetic, you can use the way of friction magnetic, wipe the iron magnet with any level of the magnet in one direction, generally wipe a dozen times can be repaired magnetic, or direct current 12v wire around the magnet, the power can be re-complex magnetic, you can also use a strong magnetic rare earth permanent magnet, the ordinary magnet for magnetic impact