Ishan asked her, “ Why didn't you tell me ?” This sentence can be reported as
AIshan asked her why she hadn't told him.
BIshan asked her why didn't she tell him.
CIshan asked her why hadn't she told him.
DIshan asked her why she hasn't told him.
AIshan asked her why she hadn't told him.
BIshan asked her why didn't she tell him.
CIshan asked her why hadn't she told him.
DIshan asked her why she hasn't told him.