Question: Do we have to make up prayers that we missed? What if it was many years that we did not pray?
Yes, obligatory prayers must be made up if they were left off intentionally or out of forgetfulness. One who makes up five days of prayers per day is not deemed to be slacking in this regard. Prayers missed while traveling, are made up in the same manner they would have been prayed (i.e. shortened).
Written by Shadee Elmasry
Source: Matn al-Akhdari
يَجِبُ قَضَاءُ مَا فِي الذِّمَّةِ مِنْ الصَّلَوَاتِ وَلَا يَحِلُّ التَّفْرِيطُ فِيهَا، وَمَنْ صَلَّى كُلَّ يَوْمٍ خَمْسَةَ أَيَّامٍ فَلَيْسَ بِمُفَرِّطٍ وَيَقْضِيهَا عَلَى نَحْوِ مَا فَاتَتْهُ إِنْ كَانَتْ حَضَرِيَّةً قَضَاهَا حَضَرِيَّةً، وَإِنْ كَانَتْ سَفَرِيَّةً قَضَاهَا سَفَرِيَّةً سَوَاءٌ كَانَ حِينَ الْقَضَاءِ فِي حَضَرٍ أَوْ سَفَرٍ.