بسم الله والحمد لله والصلاة والسلام على رسول الله وبعد
Celebrating birthdays is like self glorification. People celebrate their life every year and forget the reality that death is promised to all. The most important thing is whether we would die obeying our creator or obeying our desires.
And if you say that you celebrate it because you want to thank Allaah for another year in your life; then know that you should be thankful to Allaah for that everyday you live and that every breath you take. You should thank Him in the ways which Allaah has prescribed and the way the Prophet صلى الله عليه وسلم has described. Singling out one day like this is not the way we were taught by our Prophet and if there was any benefit in it, he صلى الله عليه وسلم would have informed us.