How did hamlet lose his joy?

Hamlet lost his joy primarily due to the traumatic events surrounding his father's death and his mother's hasty remarriage to Claudius. The revelation of his father's murder by Claudius deepened his despair and fueled his existential crisis. Additionally, Hamlet's struggle with feelings of betrayal and his inability to take decisive action further exacerbated his melancholy, causing him to become increasingly isolated and disillusioned with the world around him.