__________ (Recipient Details)
Date: __/__/____ (date)
Subject: Apology for not attending __________ (event name)
I am writing this letter to express my apology for not attending the _____________ (event name) that was due on __/__/_____ (date) regarding ____________ (mention event details). I admit my mistake and I wanted you to know that due to __________________ (mention reason for not attending).
I have always been punctual and I apologize for this unprofessional behaviour and I seek your forgiveness regarding this matter. Furthermore, I hope that you will understand my situation and accept my apology. I promise you that this will not happen again in future.
_________ (Contact number)