。
What on earth has gotten into her, I wonder?
Literal
She [topic-は] on-earth how-did-and-end-up [explanatory-のか] [I wonder-かしら].
どうしちゃった is the casual contracted form of どうしてしまった ('what ended up happening / how came to be like that'). The contraction route: どうして → どうしして → どうしちゃ + った, where ~てしまう regularly contracts to ~ちゃう in casual speech (~でしまう → ~じゃう). The rhetorical question 一体どうしちゃったのかしら expresses surprised concern about a change in someone's behavior — 'what's gotten into her?' The のかしら closes the sentence with the explanatory の plus the feminine-flavored sentence-final かしら, marking soft self-directed wondering. This is a classic mom-or-aunt observation about an out-of-character moment.