Reebok faced challenges in the early 2000s including losing market share to Nike and being seen as less fashionable and innovative. To turn things around, Reebok launched a new marketing campaign, partnered with celebrities to attract younger audiences, introduced innovative new products, and focused on improving the customer experience both online and offline. These efforts led to increased sales and market share gains for Reebok and a renewed perception of the brand as innovative and popular among young people.