I have struggles with dry hair a lot throughout my life because I have thinner hair so it doesnt hold a lot of moisture. One thing that I do that works great is about once a month I lather mayonnaise in my hair and leave it in for about 15 minutes. I know it sounds disgusting but the oils in mayonnaise are really good for you scalp and just bringing your hair back to life. If you don`t feel like putting mayonnaise in your hair, you can buy some products made for your hair. A great product that will moisturise your hair is anything with Moroccan oil or coconut oil in it. Your hair is dry because its lacking essential oils that our scalp naturally produces. By supplying your hair with products that have natural oils in it you are going to be putting those oils back in.