What should a person who performed the Hajj as Mutamatti' in the year 1420 AH do now, given that he did not offer the sacrificial animal (hady) and did not fast three days in Makkah?

If you are able to slaughter the hady yourself or by appointing someone, then do so. If you are unable, then you must fast ten days in your home country: three days first, then break your fast for four days (the day of Nahr and the days of Tashreeq), in addition to the days it takes for you to return to your country from Mecca, and then complete fasting the remaining seven days. It is essential to gain a deep understanding of the act of worship before embarking on it and to ask people of knowledge.