Notification Center frozen in macbook pro with Yosemite 10.10.3 My notification center is completely frozen.  It's still in the upper right hand corner of my screen, but when I click on it, nothing happens. I do not get any notifications in a popup window when I receive a message from iMessage or Facebook like I had been.  I do still get a little red 1 on my iMessage app in the dock, though.  

I have seen other forums with people having this issue being able to force quit notification center from activity monitor, but my activity monitor does not show notification center anywhere.  This same problem actually happened to me before few months ago, and after searching FOREVER I found out how to kill the application from terminal.  This does not work for me now, as when I type in "killall NotificationCenter" into the terminal it comes back saying "no matching processes belonging to you were found." 

I have spend a bit of time searching forums for this problem again, and have tried typing other things into terminal and they don't work either (killall -3 NotificationCenter; killall -9 Notification Center, some other commands that are supposed to restart all running programs).  I've also rebooted my computer.  

I just had an update for "Remote Desktop Client Update version 3.8.4" that was automatic last night, and I first noticed this problem this morning, so that might have something to do with it. This is very frustrating so if anyone can help me that'd be awesome! I'm not super knowledgeable about computers so please give detailed directions if you can.
The simplest and least destructive way to stop processes that run in your user space is to logoff, and logon again.

If you kill a process, it can't save any data correctly. Most system processes have good routines to handle this, but that slows things down the next time it starts and can leave things in a state where you need to clean up the mess by hand.

Logging out and back in will minimize the risk of causing further issues.