You may not want to be friend to every other person on Facebook and only add known people to Facebook profile. You can easily block people on Facebook, whom you do not want to interact on Facebook. However while using this block feature, you may accidentally block and report Facebook user whom you want to remain friend. You can easily reverse block friend routine and unblock any blocked Facebook person from Privacy settings.
Unblocking people on Facebook
1. After Facebook login, goto Privacy Settings page by going to Account > Privacy Settings at top right.
2. Click ‘Edit your lists’ link under Block lists option at the botton of Privacy Settings page.
3. All the blocked Facebook users will be listed under ‘Blocked users’. Click Unblock button next to specific Facebook user to unblock them.
What about reversing ‘Report friend’ action
Please note, every reported content or users is NOT blocked / removed. Facebook team checks reported profiles and content for specific abuses. If you have accidentally reported someone, then this action should not cause issue to reported friend. Also, you can be friend to that person again by unblocking him / her using above procedure.