Have you had a change of heart? Did you unfriend someone only to regret this decision a couple of days or weeks later. Would you like to mend the relationship? The first step to repairing the relationship is to re-establish an online connection - it's time to re-friend. First go to your former friend's profile page by typing his or her name into the search field at your favorite social network. Once you're on the profile page, there should be a standard friending button. Click this button and hope for the best. You can also generally send him or her a message to get things started.
Ok now that we've gone through the mechanics of re-friending let's take a step back and figure out a general plan for rekindling an old friendship.
Make sure that you take some time and cool off before trying to rekindle an old friendship. Do your best to view the situation with rational thinking and logic.
Take the initiative and reach out but notice if the other person is not making any effort in return. Rekindling is a two-way street and if you keep getting shot down, chances are that your former friend isn't concerned about reconnecting with you.
Your first outing with a former friend should be a low pressure situation. Think about inviting him or her along to an outing that you've already attended. Perhaps you can add them to the guest list for a dinner party that you're already throwing.
Before you get to rekindling, think about what qualities are truly important to you in a friend. This will help you decide what you can forgive and forget and what friendship transgressions are true deal breakers.
Don't hesitate to apologize if you're the one at fault. Even if you think that you're former friend knows what you've done, clearly accepting responsibility for it allows both of you to move forward.