I shampoo my hairs regularly. but still my hairs still remains dirty ... what should i do ?

Re-evaluate the prob: The information you provide is that 1) you regularly wash your hair with shampoo and 2) You are troubled by a characteristic of your hair that you describe as "dirty" . I think we can assume that unless your hair is covered with tar, that after a thorough shampoo your hair is not full of dirt. Accept this assumption, and after shampooing take another close look, and describe what you see and feel