When viola enter s in scene 2what catastrophe has occurred?

When Viola enters in Scene 2 of Shakespeare's "Twelfth Night," she has just survived a shipwreck that has separated her from her twin brother, Sebastian. Believing he may have drowned, she is devastated and feels lost in the unfamiliar land of Illyria. To ensure her safety, she decides to disguise herself as a young man named Cesario, setting off a series of events that drive the plot forward.