Do you mean you were separated for 10 years? If so, it may be hard at first but just start by picking up from last time you saw each other......GOOD LUCK!
First of all it depends on what you did for your friend to not want anything to do with you if it is really bad you might want to let them cool off for a little while cause you might just make things...
by apologizing to them.try saying "im sorry for what ever i did" or "im so so so sorry,i didnt now what i was doing"or "i just wanted to now if you would give me another chance of being your best...
That would depend why your not friends to begin with. You will have to apologize and talk to one another about what was wrong to begin with to see if its possible that you could be friends again.