What should I do if I was reciting a certain part of a Surah in an obligatory prayer, forgot the following verses, and continued failing to remember them despite my attempts? Should I stop the recitation and shift to bowing or recite another Surah which I memorized well?
All perfect praise be to Allaah, the Lord of the worlds. I testify that there is none worthy of worship except Allaah and that Muhammad, sallallaahu ‘alayhi wa sallam, is His slave and Messenger.
If you forget a verse of a Surah other than Al-Faatihah or even get confused about it so that you fail to remember it, and none of those whom you lead in prayer corrects or reminds you, in case you are the Imaam; then you have two options: either to end the recitation and bow; or skip to the verse that follows it, recite another verse or even another Surah.
Abu Daawood spoke about this in his book As-Sunan, in the "Chapter of correcting the Imaam in prayer.” He narrated through his own Isnad (chain of narrators) that Al-Miswar ibn Yazeed Al-Maaliki said:
I attended a prayer with the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, wherein he forgetfully skipped some verses during the recitation. Thereupon, a man said to him: "O Messenger of Allaah, you did not recite such and such verses." So the Messenger of Allaah, sallallaahu ‘alayhi wa sallam, said to him: 'Why did you not remind me of them?'" [Abu Daawood]
Furthermore, it has been narrated on the authority of Abdullaah Ibn ‘Umar that he said that the Prophet, sallallaahu ‘alayhi wa sallam, once got confused while reciting the prayer. After ending the prayer, he, sallallaahu ‘alayhi wa sallam, said to Ubayy : "Have you offered the prayer with us?" Ubayy replied in the affirmative, so the Prophet, sallallaahu ‘alayhi wa sallam, asked him, saying: "Then what prevented you?" (Meaning: from correcting me)
Al-Badr Ad-deen Al-‘Ayni said: "The one led in prayer should not hasten to correct the imam. Moreover, the imam should not keep repeating the same verse or remain silent. Rather, he should bow if it is due or skip to another verse."
Allaah Knows best.
You can search for fatwa through many choices