。
She blamed her failure on bad luck.
Literal
She [topic-は] failure [object-を] bad-luck [blame on-のせいにした].
~のせいにする means 'to blame on' — literally 'to make something the fault of.' 悪運 (bad luck/misfortune) becomes the scapegoat. 失敗 (failure) is what she's attributing to luck rather than her own responsibility. The pattern Aを Bのせいにする = 'to blame A on B' is a very useful construction for discussing responsibility and excuses.