ANSWER:

As Muslims, we follow the Quran and Sunnah. Allah has perfected this beautiful religion so anything that already exists in it, we do it, per our sunnah, and anything that is not in our religion, we reject – especially when these innovations come from the Jews and Christians as we are instructed not to imitate or resemble them. Muslims do not celebrate anniversaries as this would be partaking, endorsing, and approving of such falsified celebrations and would be imitating the disbelievers.  

Good innovations? Bidah hasana? | By Assim Al Hakeem

Please guide me regarding bid’a,Is bid’a not an unlegislated act in islam done with the intention to earn reward.how come celebrating marriage anniversary etc is a bid’a .no one seeks to get closer to Allaah or earn reward through these acts.I don’t celebrate any such events but if some one is to ask me this question,I don’t have an answer.