text notifications not showing up

[AC Question]

I had a text message notification in the notification window and every time I clicked it, I was redirected to a blank text message composing page. Even though I viewed the text message, I wasn't able to swipe the notification away and my LED light continued to blink but eventually some setting page randomly popped up and gave me the option of not allowing text messages in the notification window, I was clicking around on my phone and accidentally unchecked the box so the text message notification did go away but now I never get any more notifications from texts and I don't know where to find that option to change it back. It's not in the regular messages/ settings/ notifications options. And now my LED lights blinks green when there aren't any notifications to show. I want my text messages to show up again in the notifications window and to figure out the mystery of why my LED light blinks green with no notifications to show for it.