Windows 10 notification center hotkey

1. Open the Settings app
2. Go to System

3. Go to Notifications & actions and scroll down to find "Show notifications from these apps"

4. Click on Outlook 2013
5. Enable notifications and notification banners

Might be it is disabled, Try below method.

Go to Local Group Policy Editor. If you cant make that out than go to run and write this command - gpedit.msc to open local group policy editor.

In the left pane - -> User Configuration - -> Administrative Template -- > Start Menu and Taskbar - -> in the side panel find - "Remove Notification and Action Center". - -> Double Click on that - -> if it is enabled then make it disabled. Restart your PC.

Might you get the solution.

Source taken from : http://www.tenforums.com/tutorials/6004-action-center-enable-disable-windows-10-a.html

OR

you can do something like this :

Start Menu - - > Setting - -> System - -> Notification and actions - -> Turn system icon on or off. - -> Action Center - -> if it is off - -> On it.