You should note that it is not permissible for a Muslim to think of the sins from which he has repented as being too great, for the mercy, pardon and forgiveness of Allaah are greater than his sins. 

If the sins had to do with other people, then it is obligatory to restore people’s rights to them. If the sin has to do with something that is between a person and his Lord, then it is sufficient for him to repent, seek forgiveness, regret what he did and resolve not to go back to those sins. It is not a condition of repentance that the hadd punishment be carried out on the repentant person. He should conceal himself with the concealment of Allaah, Achieving sincere repentance is better than confessing so that the hadd punishment may be carried out. 

This person has repented well and has given back to people what is rightfully theirs, so he should not let the Shaytaan come and spoil his repentance. 

It should be noted that Allaah turns the bad deeds of the repentant into good deeds. Allaah says (interpretation of the meaning): 

“And those who invoke not any other ilaah (god) along with Allaah, nor kill such person as Allaah has forbidden, except for just cause, nor commit illegal sexual intercourse and whoever does this shall receive the punishment.

69. The torment will be doubled to him on the Day of Resurrection, and he will abide therein in disgrace;

70. Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allaah will change their sins into good deeds, and Allaah is Oft‑Forgiving, Most Merciful.

71. And whosoever repents and does righteous good deeds; then verily, he repents towards Allaah with true repentance”

[al-Furqaan 25:68-71]

The offenses which the sultan (Muslim ruler) hears of are the ones for which the hudood punishments must be carried out. As for those of which he does not hear, then it is better to repent from them and to conceal oneself with the concealment of Allaah. 

The scholars of the Standing Committee said: 

If the shar’i ruler hears of offenses and they are proven by sufficient evidence, then the hadd punishments must be carried out, and it is not waived by repentance, according to scholarly consensus. The Ghaamidi woman came to the Prophet (peace and blessings of Allaah be upon him) asking him to carry out the hadd punishment on her after she had repented, and he said concerning her: “She has repented in a manner that if the people of Madeenah were to repent in this way, it would be sufficient for them.” But despite that he carried out the shar’i hadd punishment on her. But no one has the right to do that but the sultaan. 

But if news of that offence does not reach the sultaan, then the Muslim should conceal himself with the concealment of Allaah and repent sincerely to Allaah, so that Allaah may accept his repentance. 

Fataawa al-Lajnah al-Daa’imah, 22/15 

And they said – responding to one who wanted to carry out the hadd punishment and who was not sure that repentance from zina would be accepted – 

If a person repents to his Lord sincerely, then Allaah has promised that He will accept his repentance, and will compensate him with reward. This is by His kindness and generosity. Allaah says (interpretation of the meaning): 

“And those who invoke not any other ilaah (god) along with Allaah, nor kill such person as Allaah has forbidden, except for just cause, nor commit illegal sexual intercourse and whoever does this shall receive the punishment.

69. The torment will be doubled to him on the Day of Resurrection, and he will abide therein in disgrace;

70. Except those who repent and believe (in Islamic Monotheism), and do righteous deeds; for those, Allaah will change their sins into good deeds, and Allaah is Oft‑Forgiving, Most Merciful.”

 [al-Furqaan 25:68-70]

The conditions of repentance include: giving up the sin, regretting what one has done and resolving not to go back to it. If the matter involves the rights of other people, then one must also ask them for forgiveness. 

It was narrated from ‘Ubaadah ibn al-Saamit (may Allaah be pleased with him) that when the women gave their oath of allegiance (bay’ah) to the Prophet (peace and blessings of Allaah be upon him), he said: “Whoever among you is faithful (to this oath), his reward will be with Allaah. Whoever does any of these things (wrong actions) and is punished for it, that will be an expiation for him. Whoever does any of these things and Allaah conceals him, then it is up to Allaah: if He wills He will punish him and if He wills He will forgive him.” 

The Prophet (peace and blessings of Allaah be upon him) encouraged sincere repentance. In the story of Maa’iz he said: “Why did you not leave him alone, perhaps he would have repented and Allaah would have accepted his repentance.” Maalik narrated in al-Muwatta’ from Zayd ibn Aslam that the Messenger of Allaah (peace and blessings of Allaah be upon him) said: “O people, the time has come for you stop transgressing the sacred limits set by Allaah.  Whoever commits any of these evil actions, let him conceal himself with the concealment of Allaah, for whoever discloses his actions, then we have to carry out the hadd punishment (that is prescribed in) the Book of Allaah.” 

So you have to repent sincerely, offer prayers regularly in congregation and do a great deal of good deeds. 

Fataawa al-Lajnah al-Daa’imah, 22/44,45 

For more information please see the answers to questions no. 264, 23485, 10983, 728. 

And Allaah knows best.