Receiver’s name,
Receiver’s address,
Date: __/__/____ (Date)
Subject: Birthday party invitation
Dear ________,
I hope you are doing fine we are also fine here. I am writing this letter to you to invite you for my ________(son/daughter) birthday party on ______ (date). It’s his/her ___th birthday and all arrangements have been done. We want you to be present at the venue and provide him/her with your blessings. The venue for the party is ________(location) and the timings would be _______(time)
We won’t accept any kind of refusal from your side. Kindly be present for the event.
Thanking you,
________(Your name)
________(Address)
________(Contact number)
letterskadmin 
Rahul Sharma