this person said they pay me money for articles but he never paid and i mailed to him is thiere any legal way to get it?
Is there a legal way? Yes. Is it worth it? Hell NO. If you do a whois on his domain, or know his location or phone number, call him up or threaten to go to his house and beat the crap out of him.**Use at your own risk
It depends on a few things. One, is the person a member of the DP forums? If so, you can post negative rep so other writers know not to work with him. Two, if s/he's not a DP member, where did you two meet? Bidding sites often have dispute resolution procedures in place. Depending on the size of the project, it may not be worth the time and effort to pursue payment. If it was a $50 project, it will cost a lot more than $50 worth of your time to chase this person down and ask for payment. You might want to take the articles you wrote and sell them elsewhere (you retain the rights to the articles since you have not been paid for your work). You might even put them up on your own site and use them to generate AdSense or affiliate income. Now, if it was a large amount (hundreds or thousands of dollars), definitely pursue your payment. As a last resort, you can take legal action if the buyer continues to not pay you.
Scam. That's the problem if the person you are talking is not really a friend of yours. After they got from what they want, they will vanish like a bubble.
If you are talking about the US, the police aren't going to do anything about this. It is civil matter and they will be of absolutely no help.