I can't add events to my calendar. The + sign that used to be at the top right corner is missing.

Hi,

I've been trying to fix my iphone calendar from what other folks have written on my issue, but nothing seems to be working. I can't add any events, since the + sign is missing. I've enabled and disabled and re-enabled icloud, rebooted the whole phone on iTunes, and fiddled around with every setting with no luck. Any other suggestions?? Are there other calendar apps that work as well or better than the iphone calendar?