In the name of Allah the Beneficent the Merciful.
O Allah! I seek forgiveness of all those sins of which You have knowledge of either it is of my good deeds or evil deeds, knowledge of my whole life, or from first to last, knowingly or unknowingly or the knowledge of my sins which I have erred erroneously whether little or great, big or small, old and new, secret or open and those sins of which I am guilty of. And I ask forgiveness of You and request You to send blessings on Mohammad and the progeny of Mohammed and forgive all my excuses which I have done on Your creation and is in Your knowledge because their rights are incumbent on me and I am responsible of it.
But You can forgive them as You desire O the most merciful of all the mercifuls.
source : http://www.duas.org