Step1
Assess. First thing is to determine what it was or what was done to end the friendship? Maybe you ran off with your friend's tennis partner and it hasn't been the same since? Did you break a plate at a party? Maybe it was something that was done to you. The point is to go back into your memory, or journal or old calendars or whatever it was, and figure out what ended your friendship...or maybe you don't know, which is fine as well.
Step2
FORGET THE PAST! A very nice old Nun once told me, "The past is dead, the future, unborn." We can't live in the past. If you are going to get on with the friendship, then you need to bury the hatchet, whatever it was, no matter how painful, is it worth the price of your friendship. Believe me, if it's money, or possession it isn't worth it. Very few material things on this earth are worth the price of an honest, bonified friendship. What does it matter what you can purchase, it can always be replaced. It's the intagible things, like love that we can't buy or find in the local mall. Forget the past. Bury your grudges and move on to the next step.
Step3
Depending on how awful the seperation was, you may have to really dig deep. Figure out just how to get through to your friend. Let's say for example you were kids together who played stick ball in the alleyway with an orange tennis ball. Winning your friend back may be as simple as buying an orange tennis ball and sending it to them with the note, "Wanna have a game. I miss you. Whatever it was that set us apart, forgive me. Let me hear from you." You may have to go way back if it's a deep wound.
Step4
You've got history. Remember that. It's this history which can bring you back together. Ask for forgiveness, even if you don't think that you did anything wrong. Think of it this way, you want to forgive your not being friends, which is the greatest injustice to the planet.
Step5
Send cards, flowers, gifts, wooden totem poles, whatever it takes. Send them a clown reciting a silly poem you wrote in the third grade. Think outside the box. Don't be afraid to get creative. You need to let them know that you are still that wonderful friend that THEY remember. And if you're remembering them, then chances are they're still thinking of you...it's that whole psychic connection thing.
Step6
Once you've said your piece, sent your cards, made your calls, tried to hook up and get back, your part is done. Now let them come to you. Believe me when I tell you this, it is better to make peace with your old friends, to have gone to your grave without having tried to resolve the issues. You will feel better about this. And you are the better person for having tried. And on the bright side, you probably will get your old friend back.