How to ask your long distance friend to return my money in a polite way ?

Well, you can say. Hey, I would have never brought it up, but I need money urgently. I am short on cash and need to pay someone or some expense ( you cam make up this person based on somone your friend doesn't know).

I guess this is the best way without complicating things too much. Has worked for me quite a few times.

If your friend starts to make excuses, you may have to talk a bit strictly.