Generally be forgiving but just a little wary while i had time to see if they were genuine or had some other motive.
It would depend on a lot of things, for example, who they were, how I feel about them, what is going on in my life at the moment etc..
We can't or shouldn't live in the past. If your long lost bff makes the attempt to renew your relationship, it might be the pick me up you need. If not, you have the option to can it.
But we have to live in the now.
I would still be friends with them, I don't just stop being friends with people because they're away.
Forgive forget and move on!!
Take it slow, while being firm in your position.
Forgive them and continue, atleast they made the effort to contact you now. Would be stupid to ignore it and who knows, maybe they really need a mate at that point in time and you could be their last hope.
I'd be inclined to think that he wants something or he may need you now that he has no one else!
Resume the friendship...I often go for long periods of time without calling any-one and they all seem to not care....well, perhaps they just don't like me...lol