It is narrated from Nafi' that Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) fell unconscious and lost his senses, and he did not make up the prayer.
And Imam Malik (may Allah have mercy on him) said: That is because the time had passed; as for whoever recovers while he is within the time, he will pray.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1818
The father of Abd al-Rahman bin Abi al-Zinad (may Allah have mercy on him) says: I found the jurists of our (region), who followed the opinion of the Successors of the people of Madinah, saying (and he mentioned some rulings, among them) that prayer is not due from an unconscious person, unless he recovers while he is within the time of a prayer, in which case he will pray it; and he will make up the fasting. And if the unconscious person recovers before the sun sets, he will pray Zuhr and Asr, and if he recovers before dawn breaks, he should pray Maghrib and Isha. They said: The menstruating woman will also do the same when she becomes pure before the sun sets or before dawn breaks.
A musnad hadith has been narrated on this, and there is weakness in its chain. And Allah knows best.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1819
Al-Qasim asked Sayyidah Aishah (may Allah be pleased with her) about a man who falls unconscious and misses the prayers of a day or two days or more than that. She said that the Messenger of Allah (peace and blessings be upon him) said: "There is no making up for him, except the prayer in which he regains consciousness; he will pray that."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1820
Sayyiduna Ibn Umar (may Allah be pleased with them both) narrates the like of this from the Prophet (peace and blessings be upon him).
Al-Bukhari mentioned him in al-Tarikh and said: There is a problem (nazar) in him. Al-Hakam bin Abdullah al-Ayli was abandoned by them; Ibn al-Mubarak used to declare him weak, and Ahmad bin Hanbal forbade (narrating) his hadith.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1821
It is narrated from Yazid, the freed slave of Ammar (may Allah be pleased with him), that Ammar bin Yasir (may Allah be pleased with him) fell unconscious during (the times of) Zuhr, Asr, Maghrib and Isha, and he recovered at midnight, then he made up the Zuhr, Asr, Maghrib and Isha prayers.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1822