Answer:
Hi, (Friend) It's with huge regret that I write this letter to present my apologies for missing your birthday party.I'm extremely sorry for having missed your birthday celebration. I know that it was a special night for you and I can't say how much I'm sad to miss this special occasion to be around you.I couldn't come to your party because ( explain why) I am deeply sorry and Hope you understand. I can make it up to you soon!
Happy Birthday!
Best of wishes,
(Your Name)
Explanation:
Hope this helps :)
