Sample Apology Letter to the Manager

To
(Receiver’s Name)
(Position)
Dear Sir,
I would like to express my deep regret and heartiest apology to you because of my poor performance at work. I know that I am coming in late and not completing my work on time. For this kind of inconvenience, I am truly sorry. I also take full responsibility of this.

Around 3 weeks ago, my daughter was met with an awful accident. Her situation was very critical. She was in I.C.U for 7 days. I was very stressful on those days. With the blessings of almighty, my daughter is doing better now. My daughter has settled back in at home now. Thankfully things have begun to calm down.  Right now, I am ready to give my attention back to my job again. I promise to you that I do only my best work from this point forward.

I am also thankful to you for your understanding during the difficult time. I really appreciate with your leniency over the past couple of weeks and I promise that you won’t regret it. Please accept my most sincere apologies for my poor performance during last month.

Sincerely yours,
(Your Name)
(Your position)
(Name of the Company)