拒绝邀请生日聚会写一封信，英语作文，好学英文网提供要点如下：

1.谢谢你的邀请;2.我妈病了我不能去;3.祝你生日快乐;

Dear Mary,　　　　　　 26th Oct 2009

Thanks for inviting me to your birthday party this Saturday. We have not met for so long, I am very happy to have a chance to catch up with you and celebrate your birthday. Unfortunate, my mother is down with a bad flu. My father has been assigned to work overseas. I am the only family member available to look after her. From hxw.red.

Therefore I am not able to attend your party. I have selected a very special birthday present for you.

John will send the present to you on my behalf. I hope you will like it. Please don't be made at me. I will also find another time to have dinner with you.

Happy birthday!

Yours faithfully,

Peter