Look, damaged hair can't be repaired. If it's to the point where it's not responding to band-aid type treatments you have one of two options. You can wear your hair damaged or cut it off. Nothing is stopping you from cutting it off, but you and your personal standards of beauty.

Also I'm hearing a lot about moisture, but damaged hair generally requires protein treatments. It's a common misconception that all dry hair is damaged. Some people, such as myself, just have dry hair and scalps. It's sounds like you naturally don't produce much oil and that your hair is damaged. Balance the moisture with protein. If nothing works my best advice is cut it off.