notification center won't open
I am working on a Mac Book Pro Version 10.10.5
I can't open my notification center... I don't get iMessage notifications, email notifications, etc. and when I go to the upper right corner and click on the notification icon, nothing happens. I have checked to make sure all of the notification settings are "on". It hasn't been working for a while, so I updated my software and it still isn't working.
MacBook Pro with Retina display, OS X Yosemite (10.10.5)