It depends on what kind of brain damage. Neurons do not grow back or repair themselves, so physical damage is permanent. Emotional/psychological damage, however, can be recovered from with therapy or...
When a neuron is damaged, the glial cells remove the neuron, and work to protect the other neurons.Glial progenitor cells can form into neurons or glial cells, depending on what type was damaged....
While the answer to this question may seem obvious, it is actually a fair question to ask. Some brain damage does in fact destroy vital centers of the brain that are necessary for functioning...