Allah (swt) says in the Quran:
Say: "O My servants who wronged against their souls, do not despair of Allah's mercy! For Allah forgives all sins; for He is indeed Forgiving, Compassionate."
"...and repent to Allah all of you O believers in order that you may be successful."
"Truly, Allaah loves those who turn unto Him in repentance and loves those who purify themselves"[al-Baqarah 2:222]
The Prophet (peace and blessings of Allaah be upon him) said: "Our Lord comes down to the lowest heaven when one-third of the night remains, and says, 'Who will call upon Me so that I may answer him? Who will ask Me so that I may give to him? Who will seek My forgiveness so that I may forgive him?'" (Narrated by Muslim, no. 758)