If you have actually blocked someone inadvertently or altered your mind about the block, however, it is also reversible. You can alter your Personal privacy settings to unclog and permit someone back into your Facebook world.
How To Unblock Someone On Facebook Mobile
1. Click the down arrow beside "Account" at the leading right of any page on Facebook.
2. Click "Privacy Preferences" from the Account menu.
3. Click the "Edit Your Lists" link under the Block Lists heading. It is at the bottom center of the page.
4. Click the "Unclog" link beside the name of the person you wish to unblock. A list of the people you have actually obstructed is found under the Block Users area.
Pointer
Unblocking somebody does not automatically put that person back in your buddy list. You need to add the freshly unblocked individual as a friend and await them to confirm the request.
And one more thing please don’t forget to share this awesome trick to use the How To Unblock Someone On Facebook Mobile with your friends.