The Prophet ﷺ said: "Whoever forgets a prayer should perform it as soon as he remembers it; there is no expiation for it except that: {and establish prayer to remember me.}" [Sahih Bukhari 597, Sahih Muslim 684]
So the practical steps are:
1. Pray it immediately when you remember. Don't delay it further once you recall it. The missed Fajr is prayed as the normal 2 obligatory rak'ahs, exactly as you would pray it in its time.
2. Pray them one by one, in order. If you missed several Fajr prayers, make them up individually — each one is 2 rak'ahs. If you know how many you missed, pray that number. If you're unsure, pray what you reasonably believe you missed until you feel confident you've covered them.
3. Don't combine them with other prayers or replace them with something else. The hadith is clear that nothing expiates a missed prayer except praying it itself.
4. If you missed the sunnah (the 2 rak'ahs before Fajr), it's recommended to make those up too, since the Prophet ﷺ was extremely consistent with them. 'A'ishah (may Allah be pleased with her) said: "The Prophet ﷺ did not observe a voluntary prayer more regularly than the two Rak'ahs of Fajr." [Sahih Bukhari 1169, Sahih Muslim 724] Some scholars say the sunnah of Fajr can be made up after the Fajr prayer or later, but the obligation is the 2 fard rak'ahs.
5. Be consistent going forward. Allah's mercy is vast — He says: {And establish prayer at the two ends of the day and at the approach of the night. Indeed, good deeds do away with misdeeds.} [Surah Hud: 114] The five daily prayers are an expiation for minor sins, so return to praying on time with sincerity.
A practical tip: set a reliable alarm for Fajr, and if you do oversleep, pray as soon as you wake — don't wait. You can also use the prayer times section in your Al Muslim Plus app to set accurate Fajr reminders for your location, and check the Qibla compass before praying so your prayer is valid.
If your situation involves many years of missed prayers or you're unsure how to estimate them, it's best to consult a qualified scholar for guidance tailored to your case.