How do I repent to Allah for many sins known only to Him?

The faith of a Muslim may weaken, and they may fall into sin. Allah is kind to His servants, and His mercy encompasses all things. So, whoever repents after having wronged themselves, Allah will accept their repentance, for He is Oft-Forgiving, Most Merciful. Allah Almighty commanded the believers to make sincere repentance to attain His mercy and His Paradise. The door of repentance is open until the sun rises from the west. Repentance is not merely a word on the tongue; rather, for it to be accepted, it requires immediate cessation of the sin, regret for what has passed, firm resolve not to return to it, restitution of wrongs and rights, and that the repentance be made before the onset of death. Allah is the Accepter of Repentance, Most Merciful; He loves those who repent and accepts their repentance. If a disbeliever embraces Islam, Allah replaces their evil deeds with good deeds and forgives them what has passed. Allah is Oft-Forgiving, Most Merciful; He loves repentance from His servants. If a servant’s sins are great and they have wronged themselves excessively, then they repent, Allah will accept their repentance and forgive all their sins. Our Lord, the Blessed and Exalted, descends every night to the lowest heaven in the last third of the night, saying: "Who is there that supplicates Me, that I may answer him? Who is there that asks of Me, that I may give him? Who is there that seeks My forgiveness, that I may forgive him?" The human soul is weak, so one must frequently repent and seek forgiveness. Allah loves repentance from His servant, accepts it, and rejoices in it.