Facebook offers settings so that you can control who sees what on your profile. For instance, you would make it impossible for a friend to see who posts and post messages themselves on your Wall. If you have an inability to post on a friend's wall yourself, it could be that you've been blocked from seeing or posting on the wall. Looking for a few clues can alert you to the possibility that you've been blocked from the Wall, but not the profile or friends list of a Facebook friend.
Sign into your Facebook profile and click "Friends," which is located underneath your profile picture. Enter the name of the friend you think has blocked you in the search field at the top of the Friends page.
Locate the friend you think has blocked you and click on her profile picture or name to enter her profile.
Search the page for the ability to post on his wall. This can be identified by a large bar at the top of your friend's profile page that says "Write Something..." in it. Should you locate this bar and can type a message into the bar, you have not been blocked from the wall. If this bar is missing completely, you've been blocked.
Check your friend's Wall postings to see if you're able to see certain activity. If you're able to see your friend's Facebook activity in the way of adding friends, changing personal information and joining fan pages, but you don't see any messages from other friends on the Wall, it's likely that you've been blocked.