If you have actually blocked somebody accidentally or altered your mind about the block, however, it is likewise reversible. You can change your Privacy settings to unclog and enable somebody back into your Facebook world.
If I Unblock Someone On Facebook
1. Click the down arrow next to "Account" on top right of any page on Facebook.
2. Click "Personal 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've blocked is discovered under the Block Users section.
Tip
Uncloging somebody does not instantly put that individual back in your friend list. You should add the freshly unblocked person as a good friend and await them to verify the demand.
And one more thing please don’t forget to share this awesome trick to use the If I Unblock Someone On Facebook with your friends.