Thank you for asking me.
First you must understand that the five precepts are not commandments. We undertake to observe the five precepts TO THE BEST OF OUR ABILITIES. They are moral principles for us to live by, to the best of our abilities. I don't think an average person can live through without ever breaking the precepts.
The Buddha prescribed these precepts for us to live our lives peacefully. However, at times certain conditions may not allow us to rigidly adhere to them. It is at such times that we must use our common sense and human intelligence to make decisions. That is the time when we need to use our wisdom and freedom of choice. Sometimes we might even have to compromise for the greater good.
Under normal circumstances if we really make mistakes then it is up to us to realize and to do better the next time. If you hurt someone then you may ask forgiveness from the person. However, if the mistake is self inflicted, there is no one to forgive you. You only need to forgive yourself being mortal, and to try harder the next time. This is the Buddhist way. We are not perfect beings. That's why we are striving to better ourselves. We keep on improving by making mistakes. Don't worry. Keep on practising and you will be on the right track.