A buyer sent me contact information in my inbox do it can create Problem for me .what i have to do
No, lot of buyers do such thing. The only way you can face problem is if you urge them to contact you and do work out of Fiverr.
I think there is a topic in tip section about this problem, the title is “how to handle bad buyers” or something like that
The best thing you can do here is school them on Fiverr’s TOS, and let them know that all conversations and business must take place within the site. If they persist, then report them to Fiverr CS for rule violation. DO NOT CONTACT THEM ANY OTHER WAY!