If a person forgot to say Yaale V'yovo in Shachris or Mincho...

Nshei Chabad Newsletter / If a person forgot to say Yaale V'yovo in Shachris or Mincho, the Halocho is as follows: A) If he reminds himself before he says the word Hashem immediately preceding Hamach'zir Sh'chinosoi L'tzion, he goes back and says Yaale V'yovo. B) If he reminds himself after he says the word Hashem immediately preceding Hamach'zir Sh'chinosoi L'tzion, he should say Lamdeini Chukecho and then, go back and says Yaale V'yovo C) If he said Hamach'zir Sh'chinosoi L'tzion but did not start Modim, he says Yaale V'yovo right there and continues with Modim. D) If he began Modim but did not yet say the last Yih'yu L'rotzon immediately before Oiseh Sholom B'm'roimov, he goes back to R'tzei and says Yaale V'yovo E) If he reminds himself after the last Yih'yu L'rotzoin, even if he did not yet move his feet, he must repeat the entire Sh'mone Esrai (Likutei Dinei Uminhogei Rosh Chodesh., Ch. 6, Pars. 5-9).