What essential oil can be used for the nervous system or nerve damage?

Hard to say. . By definition, "alternative" is different than modern western medicine. Generally any drug, herb, treatment, or oil that stands up to rigorous scientific scrutiny is included in modern medicine. Many alternative practices, oils etc do not stand up to scientific scrutiny and cannot be shown to work.nor safe. Some could do serious harm. Check https://nccih.nih.gov/ for research.
Several ingredients. There are a few ingredients that have been well documented at enhancing nerve regeneration and providing overall nerve support. Vit B12 (methylcobolamanin) as well as acetyl l carnitine, Alpha lipoic acid, etc. I have formulated a product specifically at nerve support called neurogen® if your interested in more information www.Nutrition.Md.
? Vit b12, Cod liver. The nervous system has a limited change to recover from nervous death or sick cells. Vitamin b 12 and fish oil, omega 3 ( oil from cod liver) have been recommended but reconstruction of nerve cells can be achieved only by stem cell transplant and ordering the brain to repair the affected area ( physical therapy). Check what other drs. Have to say.