The setbacks triggered months of deep sadness and withdrawal, during which he lost weight and pulled away from those closest to him. Friends grew concerned as he distanced himself. Eventually he began performing again at events ranging from galas to state fairs, gradually reconstructing his path independently. In 2005 he put out a second album on his own terms and pursued various television and theatrical roles.
Guarini made his Broadway debut in 2010 with Women on the Verge of a Nervous Breakdown. He went on to appear in shows such as American Idiot, Romeo and Juliet, and Wicked. Starting in 2015 he took on the recurring Lil' Sweet persona in Diet Dr Pepper commercials. He has now released the book Center Stage Confidence: How to Own Your Story and Command Any Room, encouraging people to see failure as a guide and to keep pushing forward no matter what.