Forgot to say Ya’aleh Veyavo by Shacharis and remembered after Musaf:
If one forgot to say Ya’aleh Veyavo by Shacharis, then he must repeat Shemoneh Esrei. However, this only applies if one remembered prior to Davening Musaf. If, however, one already Davened Musaf and only then realized he had forgotten to say Ya’aleh Viyavo in Shemoneh Esrei of Shacharis, he does not need to repeat Shemoneh Esrei.
If one forgot to recite Ya’aleh Veyavo by Shacharis he must repeat Shemoneh Esrei if he has not yet Davened Musaf. If one forgot to recite Ya’aleh Veyavo by Mincha he must repeat Shemoneh Esrei.
If in the middle of the first three blessings of Musaf one remembered that he did not say Ya’aleh Veyavo in Shacharis what is the law?
One is to continue with the Shacharis Shemoneh Esrei even though he did not have in mind to do so when he first began Shemoneh Esrei.
 Michaber 422:1; Brachos 30b
 Admur 126:3; Rameh 25; M”A 126:3; Kneses Hagedola 422; Birkeiy Yosef 108:5 [however in Shiyureiy Bracha he retracted]; Mor Uketzia 422 [brought in M”B 422:4] rules that one is to repeat the prayer as a Tnaiy; if he must repeat it then he is repeating it as an obligation and if he is not obligated to repeat it then it is a Tefilas Nedava. The M”B ibid brings both opinions and concludes with the ruling of the Mor Uketzia ibid.
Other Poskim: Some Poskim rule that an individual who forgot Ya’aleh Veyavo must repeat Shacharis even if he remembers after Musaf. [Peri Chadash 126:3; Chida in Shiyurei Bracha 108:2; 126; Erech Hashulchan 108:4; Shalmei Tzibur 222; Zechor Leavraham Letter Reish; Shaareiy Teshuvah 108:12; 422:3; Beis Oved 6; Kaf Hachaim 108:15; 126:16; 422:8; Opinions brought in M”B ibid] Thus, if he remembered only after the time of Shacharis has passed then he is to Daven Mincha twice, as Tashlumin. The above Poskim argue on the above conclusion of the Rameh and Kneses Hagedola. The Chida in Birkeiy Yosef ruled that Safek Brachos Lihakel however he then found a Rashba who clearly implies like the Peri Chadash and hence in Shiyurei Bracha he retracted his ruling and concluded that one must repeat Shacharis. He states that if the Rameh and Kneses Hagedola would have seen this Teshuvah of the Rashba they too would have retracted their ruling.
 The reason: As in Musaf one mentioned Rosh Chodesh, and hence there is no need to invalidate the Shacharis prayer due to it lacking Rosh Chodesh. Now, although this law was only applied to a Chazan who forgot Ya’aleh Veyavo in his repetition of Shacharis and not to an individual, nevertheless, one should not be stringent Bedieved for a Yachid by a matter that we are lenient even Lechatchila for a Chazan. [Admur ibid; Rameh ibid]
 Machazik Bracha 422/1; Zera Emes 47; Mamar Mordechai; Shalmei Tzibur 222; Zechor Leavraham Letter Reish; Shaareiy Teshuvah 108/12; 422/2; Beis Oved 6; Nehar Shalom 424; Kaf Hachaim 108/16 and 422/7