He forgot to fast the third day during Hajj and fasted it after he returned home
Question

I fasted two days during Hajj because I could not find a hadiy, and I forgot to fast the third day, then I fasted it with the seven days (after I returned home). Do I have to do anything?.
Praise be to Allah.The one who forgets one of the three days does not have to do anything if he fasts it after he returns home. 
And Allah is the source of strength; may Allah send blessings and peace upon our Prophet Muhammad and his family and Companions. End quote. 
Standing Committee for Academic Research and Issuing Fatwas. 
Shaykh ‘Abd al-‘Azeez ibn ‘Abd-Allaah ibn Baaz, Shaykh ‘Abd al-Razzaaq ‘Afeefi, Shaykh ‘Abd-Allaah ibn Ghadyaan, Shaykh ‘Abd-Allaah ibn Qa’ood