How do you get my old hair back?

So when I was little I had super silky hair and by the time I reached like age 9 my hair started to get more curly and frizzy and super hard to deal with.... My mom used to blo dry my hair and curl it but I stopped its been months since I stopped using heat that will damage my hair and my hair is still the same.... All I want is my old hair back there has to be something I can use or stop doing to get it back... Can someone please help me or give me some advice?