I know that Masturbation is haram. I am 15 years old and I Masturbate alone although I know it is haram. I want to repent to Allah but will I be forgiven? I am scared that I won’t be forgive I have done it a lot of times
we know this is a major sin Islam. But we should not forget that Allah is Al Ghaffar (The Forgiving). It doesn’t matter how many times you did this sin Allah is the the most merciful. I am not telling you that you should continue this sin. You must try to give up this sin as fast as possible.
“O ye who believe! Turn to Allah with sincere repentance, in the hope that your Lord will remove from you your ills and admit you to Gardens beneath which Rivers flow “ — Quran, Sura 66 (Al-Tahrim), ayah 08
It clearly states that repentance will remove all your sins.
God accept the repentance of those who do evil in ignorance and repent soon afterwards; to them will God turn in mercy: For God is full of knowledge and wisdom. Of no effect is the repentance of those who continue to do evil, until death faces one of them, and he says, "Now have I repented indeed;" nor of those who die rejecting Faith: for them have We prepared a punishment most grievous. — Quran, Sura 04 (An-Nisa), ayah 17–18
So whenever you do sin repent as soon as possible because when the death comes none of his repentance will be accepted.
Doing sin is the nature of humans it doesn’t mean we will not be forgiven.
** Allah's apostle said, "Every son of Adam sins, the best of the sinners are those who repent." — Sunan al-Tirmidhi, Hadith no. 2499 **
It is clear to us that Allah forgives all sins but actually the Satan is giving you Waswasa that you won’t be forgiven. If someone repents and promise to never do sin again Allah will surely forgive him.