If I am leading prayer and I begin to recite the chapter (sura) after El Fatiha, but in the course of it I forget and get blocked, and the people behind me don't know the chapter neither, What must I do? May I begin to recite another chapter, should perform other acts of salat or what is the right thing to do ? Jazak Allahu khairan

All perfect praise be to Allah, The Lord of the Worlds. I testify that there is none worthy of worship except Allah, and that Muhammad is His slave and Messenger.

If the Imaam makes a mistake in his recitation in other than Al-Faatihah, and no one corrects him, then he may move to another verse, or recite another chapter or bow for Rukoo’, and the matter is flexible in this regard, Allaah willing.

Mawaahib Al-Jaleel by Al-Hattaab Al-Maaliki reads: “If the Imaam pauses, he should not be corrected until he hesitates, as he might be thinking about what he has recited or enjoying it. When it becomes obvious to him that he is not doing so, then he has three choices: He may either skip that verse, or move to another chapter and leave the one he was reciting, or bow [makes Rukoo’] if he has already recited a sufficient amount. This is in regard to all chapters except Al-Faatihah, as it is not permissible to skip it and it is an obligation to complete it.”

Al-Asl by Muhammad ibn Al-Hasan Ash-Shaybaani, the student of Imaam Abu Haneefah, reads: “If the Imaam makes a mistake he should bow [make Rukoo’] or recite another verse or another chapter.”

The same thing is mentioned in Badaa’i’ As-Sanaa’i’ by Al-Kaasaani: “The people led in prayer should not hasten to correct the Imaam, and the Imaam should not prompt them to do so; rather, he should bow or move to another verse or another chapter.”

Moreover, Badr Ad-Deen Al-‘Ayni in the ‘Chapter on Correcting the Imaam’, in his commentary of Sunan Abu Daawood, wrote: “The people led in prayer should not hasten to correct the Imaam, and the Imaam should not prompt them to do so; rather, he should bow if it is time to bow, or move to another verse or another chapter. 'Prompting' them means that he keeps repeating the verse or stays silent.”

Allaah Knows best.