How do you adjust notifications on the LG Nexus 4 I use to see notifications for Facebook and Snapchat on my phone but now I don't.  Can you tell me how to get this back.
There are two basic scenario:


You disabled the notification from the app itself.

So open the setting of the app and enable notification there

You removed the notification power of the app from system setting menu

Open settings -> Apps. Click on the name of the required app and make sure "Show notifications" is enabled.