Facebook Unblock?

Try this 

1. Go to "Privacy Settings" under the "Account" menu in the top-right
2. Near the bottom-center, click on "Edit your lists" under the "Block List" section
3. Click "Unblock" next to your friend

You'll need to re-add the person as a friend after you've unblocked them.

how to unblock friend requests & messages on Facebook?

To unblock Facebook.

From the main log in screen after entering your user name and password click on the tap at the top right part of the screen that says "ACCOUNT"

select "PRIVACY SETTINGS"

scroll to the bottom of the screen and locate "BLOCK LISTS" and click on "EDIT YOUR LIST" this will give you access to blocked friends.