Making Up Missed Prayers
A prayer missed through sleep or genuine forgetfulness is treated differently in Islamic teaching than one abandoned deliberately, and the guidance for each is different. The core principle for an unintentional miss comes from a hadith in which the Prophet ﷺ said: "Whoever forgets a prayer, let them pray it when they remember it; there is no expiation for it other than that." In practice, this means there's no extra penalty attached — the missed prayer (qada) is simply prayed as soon as it's remembered, with the same number of rakahs and the same method as it would have had on time.
If more than one prayer has been missed — for example, someone wakes up after having slept through both Fajr and part of Dhuhr — the general guidance is to pray them in the order they were originally due, then move on to the current prayer. So in that example: Fajr first, then Dhuhr, then whatever prayer is currently due. This ordering (tartib) is preferred but not always treated as strictly obligatory by every school of thought if time is short before the next prayer's window closes; the priority in that case shifts toward not missing the current prayer's window as well.
The question of prayers missed not by accident but through deliberate neglect — sometimes for extended periods — is treated as a more serious matter in the fiqh literature, and the guidance is less uniform: some scholars hold that such prayers cannot be "made up" in the same sense and that sincere repentance going forward is what's required, while others hold that qada is still owed regardless of the reason a prayer was missed. Because this touches on personal circumstances and differing scholarly positions, it's genuinely one of the areas worth raising directly with a knowledgeable local scholar rather than resolving from a general guide — the right approach can depend on specifics (how many prayers, over what period, and why) that a written article can't account for.
One practical note: prayer-tracking is one of the more common uses people make of prayer apps, partly because it makes the qada count visible rather than something to estimate from memory — which is one of the reasons this kind of tool tends to be one of the first things people look for after learning the missed-prayer rules.