One of the most beloved duas for forgiveness is the one Allah taught Adam himself after his mistake — a few honest words admitting the wrong and throwing yourself entirely on Allah's mercy.
“Our Lord, we have wronged ourselves, and if You do not forgive us and have mercy upon us, we will surely be among the losers.”— 7:23 (Saheeh International)
Ask Noor can give you this dua in Arabic and transliteration, plus more of the Prophet’s duas for forgiveness.
Ask Noor — free on the App Store