If you dream of your limb having been amputated, it means you are short of one limb. You are handicapped and lacking. You are struggling to perform even the simplest, daily chores. In waking life, this means you are severely disabled and face big challenges to survive.
Another dream interpretation is that you or your limb, has done some act which is wrong and your conscience wants to do penance, by punishing the offensive limb.
If you are an amputee in real life, this dream has different interpretations. Your dream of your amputate limb could be because of nostalgia for your former limb. This dream could have been triggered by seeing an event during your day.
Another possible reason for dreaming of your amputated limb is because it’s nerve endings may have been stimulated. The nerves do not know the limb is gone. The nerves sent a message to your brain, to create the dream.