MAIL ,CONTACTS,CALENDARS ARE MISSING ON MY IPHONE 6

I don't know what I did but when trying to add an email account to my iPad I inadvertently changed everything to Outlook. I was able to get my apple mail back on my iMac but mail is not working on my phone. I can send a message and receive it on my mac but messages are not being received on the phone. I have read that the first step to fixing this is to go to Mail, Contacts,Calendars tab in settings but it is not there? It is separated into three categories. How do i get this back and in turn get mail up again.

Thanks

Bruce