Whatsapp is somehow blocked in Background Tasks under Settings

I dont know somehow my Whatsapp are now blocked and I'm not getting my messages in real-time. I can only see them in the "Settings > Left Swipe > Background Task > Advance" tab and from there I can see Whatsapp. And Whatsapp is grayed out(cant tap on it) and Since, I cant even tap on it to make it run after I open it.

I need to launch the app to get my messages else I'm not getting any(advance menu says these apps cant be stopped but they're not even working in background until I open them) Anyone any help??