If they aren't on your blocked list, you might have unfollowed them or deactivated your account temporarily. It's also possible they have blocked you back or deleted their account.
Scroll down and tap Settings & privacy , then tap Settings . how do you unblock on facebook
This guide covers how to unblock someone on both the desktop website and the mobile app, along with what happens after you hit that button. If they aren't on your blocked list, you
From the dropdown menu, select Settings & privacy , then click Settings . select Settings & privacy