Can children restore brain cells?
I am not an expert in neurobiology, but this is what I have been able to find:

In general, the PNS (peripheral nervous system) does have remarkable neuroregeneration capabilities. However, the CNS (central nervous system), which includes the brain, has extremely limited neuroregeneration abilities. However, there are some interesting examples of CNS recovery:


  Children under six who undergo, unfortunately, a hemiectomy, whereby one half of their brain is taken out, are able to regain almost normal function because of the brain’s ability to rewire and literally take over the functions of the missing other half of the brain.


I am guessing one thing that can explain this is that in children, the CNS is still developing, and so if there is damage, the CNS can just entirely replace damaged parts (this might be different than "fixing" which is required in adults). 

Again, I am not an expert on this and would be glad to hear a neurobiologist's opinion.