Q1) What does the Noble Quran say about an individual accepting mistakes that have been made?

Q2) If a person has made mistakes in his/her life and never admits to them when asked by brothers or sisters, this person lies to them, would repentance be accepted?
---- The brothers and sisters have full evidence of the mistakes made ----

Quran said that accept your mistakes so that ALLAH forgive you and he is the only one who can forgive your mistakes and make you as clean from sins s you were at the first day. ALLAH is very kind and he love his people. It is stated in a Quran that if mankind doesn't pay any sins then ALLAH will make a community who does mistakes and then ask for forgiveness.