Wa'alaykumussalam Warahmatullahi
For the Forgetfulness of Surah Al-Fatihah, try to focus on its meaning and Insha Allah the forgetfulness will be reduced. For the forgetfulness of how many raka'ah you prayed, try to count in Salah. However, i understand that you have thought about it and it's hard to do so. Well if you forgot about how many raka'ah you do in salah, then you should do sujud sahwi
- (How to do Sujud Sahwi) When you are more in raka'ah. Or when you don't know how many raka'ah you've prayed
Narrated `Abdullah:
The Prophet (ﷺ) prayed (and the sub-narrator Ibrahim said, "I do not
know whether he prayed more or less than usual"), and when he had
finished the prayers he was asked, "O Allah's Messenger (ﷺ)! Has there
been any change in the prayers?" He said, "What is it?' The people
said, "You have prayed so much and so much." So the Prophet (ﷺ) bent
his legs, faced the Qibla and performed two prostration's (of Sahu)
and finished his prayers with Taslim (by turning his face to right and
left saying: 'As-Salamu `Alaikum- Warahmat-ullah'). When he turned his
face to us he said, "If there had been anything changed in the prayer,
surely I would have informed you but I am a human being like you and
liable to forget like you. So if I forget remind me and if anyone of
you is doubtful about his prayer, he should follow what he thinks to
be correct and complete his prayer accordingly and finish it and do
two prostrations (of Sahu).
Bukhari 401
Abu Sa'id al-Khudri reported:
The Messenger of Allah (ﷺ) said: When any one of you is in doubt about
his prayer and he does Dot know how much he has prayed, three or four
(rak'ahs). he should cast aside his doubt and base his prayer on what
he is sure of. then perform two prostrations before giving
salutations. If he has prayed five rak'ahs, they will make his prayer
an even number for him, and if he has prayed exactly four, they will
be humiliation for the devil.
Muslim 571a
Conclusion: Choose the strongest option, about how many raka'ah you prayed. If you don't even know which one is the strongest option, then pick the shortest one. (For example, if you completely unaware whether you offer 3 rakaah or 4 rakaah, then pick the lowest one, which is 3 rakaah). Then do Sujud Sahwi before salution. If you forgot to do sujud sahwi before salution, then Insha Allah for this situation you can do Sujud Sahwi too after Salution (Unless someone tell you that you are short in raka'ah. If that's the case, then offer your missing raka'ah). And Allah knows best.
- When you are short in Raka'ah and someone remind you about it:
Narrated Abu Huraira:
The Prophet (ﷺ) offered one of the evening prayers (the sub-narrator
Muhammad said, "I think that it was most probably the 'Asr prayer")
and he finished it after offering two rak'at only. He then stood near
a price of wood in front of the Mosque and put his hand over it. Abu
Bakr and 'Umar were amongst those who were present, but they dared not
talk to him about that (because of excessive respect for him), and
those who were in a hurry went out. They said, "Has the prayer been
reduced?" A man who was called Dhul-Yadain by the Prophet (ﷺ) said (to
the Prophet), "Has the prayer been reduced or have you forgotten?" He
said, "Neither have I forgotten, nor has the prayer been reduced." He
said, "Certainly you have forgotten." So the Prophet (ﷺ) offered two
more rak`at and performed Taslim and then said Takbir and performed a
prostration of Sahu like his ordinary prostration or a bit longer and
then raised his head and said Takbir and then put his head down and
performed a prostration like his ordinary prostration or a bit longer,
and then raised his head and said Takbir.
Bukhari 1229
'Imran b. Husain reported:
The Messenger of Allah (ﷺ) said the afternoon prayer and gave the
salutation. at the end of three rak'ahs and then went into his house.
A man called al-Khirbaq, who bad long aims, got up and went to him,
and addressed him as Messenger of Allah and mentioned to him what he
had done. He came out angrily trailing his mantle, and when he came to
the people he said: Is this man telling the truth? They said: Yes. He
then said one rak'ah and then gave salutation and then performed two
prostrations and then gave salutation. (Muslim)
Muslim 574a,
Conclusion: If you are short in rak'ah and someone tell you about it, then you should offer the missing raka'ah and do sujud sahwi after salution
- When you forgot to do the first Tahiyyat (Tashahhud)
Narrated `Abdullah bin Buhaina Al-Asdi:
(the ally of Bani 'Abdul Muttalib) Allah's Messenger (ﷺ) stood up for
the Zuhr prayer and he should have sat (after the second rak`a but he
stood up for the third rak'a without sitting for Tashah-hud) and when
he finished the prayer he performed two prostrations and said Takbir
on each prostration while sitting, before ending (the prayer) with
Taslim; and the people too performed the two prostrations with him
instead of the sitting he forgot. (Bukhari)
Bukhari 1230
Conclusion: If you forgot to do the first Tashahhud, you should offer Sujud sahwi before salution. For this i do not know if you can offer it after salution or not
In Sujud sahwi, you should say like what you usually say when in the state of prostration
And Allah knows best.