Magnets can lose their property if they are:
If they are heated
If they are hammered
If they are dropped from height
A magnet can lose its properties if it is heated, hammered or if it is dropped from a height. Permanent magnets can lose their magnetism if they are dropped or banged on enough to bump their domains out of alignment. Heating a magnet above the Curie temperature causes the magnetic domains to be disrupted permanently. Mild heating causes a reduction in the magnetism. However, when it cools, the full magnetism is restored.