Praise be to Allaah.
If he was conscious during that time then he has to make up
the missed prayers, standing, sitting, lying on his side, according to what
he is able to do. He should do them in the right order, with the appropriate
intention. So he should pray the prayers of the first day in order, starting
with the first obligatory prayer that he missed, then the next one and so
on, then the prayers of the second day and the third day, until he finishes.
But if he was unconscious, in that case he does not have to make them up.
And Allaah is the Source of strength. May Allaah send
blessings and peace upon our Prophet Muhammad and his family and companions.
Fataawa al-Lajnah al-Daa’imah li’l-Buhooth al-‘Ilmiyyah wa’l-Ifta, 6/17.