Missing Calendar events and tabs on iPhone

I need help with my Calendar. I always put my appointments in my calendar. I noticed, when i go to my calendar everything has disappeared. When i go to add a new event and select my main email its not showing up. So i go to settings and click on Mail. Go to my main email, Calendar Tab is removed and only Photos & Notes tab in visible. I updated my phone, removed the email. Re added the email, nothing same thing. Please any help would be great. Thank you

[Re-Titled by Moderator]

Original Title: Calendar Events