if one kidney of our body is removed

what will be the effect on the other kidney

also if within a kidney some neurons are damaged can they be formed again??

As it happens, I have only one kidney -- it's a congenital defect, not the result of an accident. What's happened is, the other kidney has taken up the slack. It's somewhat bigger than normal, and doing just fine. I call it my superkidney.

agreed and to add that if nephrons (not neurons) are damaged they can regenerate in some circumstances (depending on the cause of the injury).