How can I regain my natural hair?

When I was younger, I had the most beautiful waves. As I got older, I hated them and straightened them everyday. I want to repossess my waves that I've destroyed with heat products! My hair isn't really fried, but more used to the way that it is straight that it doesn't look wavy or straight when I let it air dry after swimming or showering. I made a mistake and I want to fix it!!