The chemical treatments, the blow dries, the hair straightener damage your hair.
It becomes rough because the scales get up. The good reflex is of course repairing the fiber by injecting intercellular cement in the cortex. Once repaired in the inside, after an adapted treatment, you will be able to use nutritive products to reinforce the lipid film.
The products are the first good reflex but the second one is to eat well ! When the diet is too rich, too sweet or too salty, the complexion becomes dull, the nails broken and your hair become delicate and/or greasy.