Here is an example of Sample Apology letter for failing to attend an event. You should modify this apology letter according to your need and situation.
Dear sir/ madam,
Subject: requesting to accept my apology for not attending an event for the celebration of the 5 yrs completion of our company and for the welfare of the blind people which is our company motto for the welfare of the people– regarding.
This is the letter to convey my apology for not attending an event for the celebration of the 5 yrs completion of our company and for the welfare of the blind people which is our company motto for the welfare of the people. First of all I should regret for my behavior and I regret for it in a very precise manner. I could not attend the event that held last night which was conducted by our office members for the welfare of blind peoples. The reason for my absence to the event is due the ill health of my child. She could not breathe properly yesterday evening. I took care of her and that’s why I could not attend the event. I hope you could understand my position. I promise you that I will not let this to happen one more time. Please accept my apology and allow me to get back to my work. And am sure this would be my last apology that am asking. And I promise you that I will not stop or pretend you from the actions you take when I do the same mistake next time and I feel I deserve the punishment you give for my behavior.