Allah the Almighty says in Quran:
" Say (on My behalf O' Muhammad) O' servants of Mine who have acted recklessly against their own selves, do not despair of Allah's mercy. Surely, Allah will forgive all sins. Surely, He is the One who is Most-forgiving, the Very Merciful. Turn passionately towards your Lord and submit to Him". (Al-Zumar 53)
This Verse of Surah Zumar is a very clear message to all those who have committed any sins that the door of reoentance is open and once they turn to Allah in repentance, they will know that Allah is Forgiving and Merciful.
Allah loves to forgive. We (mankind) have to take the first step to connect with Allah and seek His forgiveness.
Therefore, if someone has committed sins regardless of how many, when he/she repents to Allah sincerely seeking His forgiveness and pardon, He surely forgives.
In fact, believers are warned about falling into the state of despair and losing hope in the mercy of Allah.
And Allah knows best.
Mufti Ikram ul Haq
Fatwa Center of America
26 Rabi-ut Thani 1432/ March 31 2011