If you realize before saying Hashem’s name in “baruch ata Hashem mechayeh hameisim”, you go back to “ata gibor”. Otherwise you have to go back to beginning of shmona esrei.
For v’sein bracha, iff you rememberr before Hashem’s name then go back to “v’sein bracha”, otherwise go back to begining of bareich aleinu. If you said “y’hyu l’ratzon”, you have to go back to begining of shmona esrei.