You can view which accounts you have blocked in your user settings, and unblock the user(s), if desired. You can also unblock a user by viewing the user's profile page.
To open your user settings, click the Me icon in the toolbar [1], and then click the Settings link [2].
In Account Navigation, click the Blocked Accounts link.
If you have blocked any accounts, they will display on the Blocked Accounts page.
To unblock a user, click the Unblock button.
Confirm you want to unblock the user by clicking the Yes, Unblock button. After you unblock the user you will be able to view their profile and interact as normal.