123 Lane, Area 456,
City, State, Pin Code
March 2, 2012
<Mention Recipient’s Address Here>
I am really sorry. I myself can’t believe how I could forgot about <describe the occasion>! I feel like such a dork! I remembered it a day before and also I had it written on my calendar, but things have been so hectic for me lately that the date came and went before I’d even realized it. I am really sorry for forgetting about this important occasion. You must have thought me very unkind and inconsiderate.
I hope you’ll let me find a way to make it up to you. Please allow me to take you out on a dinner at your favourite restaurant. I am extremely very, very sorry! Please forgive me.
encl: <List of enclosed items goes here>