I'll make this brief, I hope one of you has had this experience.
I have a Motorola G 2nd gen and yesterday it stopped showing me notifications. It also will not let me swipe down to see notifications or anything at the top of the screen. I also cannot access quick settings when you swipe down twice. The only way I can tell if I have a notification is when the light starts blinking at the front.
I have scanned all options in settings and nothing seems to be messed up. Online I can't find any real solutions other than factory reset which I'd rather not do. Unless there is a settings reset without wiping all my data and info. And of course I've tried turning on and off. Have not installed any new apps that might be interfering.
pic related: what happens when I try to swipe down
settings
app settings all set to default
Unfortunately the option might be factory resetting or you could try a different rom like CM13.
Seems like you used screen pinning.
Check http://www.talkandroid.com/guides/android-lollipop-guides/how-to-lock-any-app-on-your-phone-or-tablet-for-guests-and-kids-in-android-lollipop/