baodo159, for a start I suggest you (if you haven't already) read their TOS, especially the parts that can be linked to your case ->
We may in our sole and absolute discretion, immediately and without prior notice: (a) suspend, restrict, or terminate your access to any or all of the Services (including limiting access to your Wallet), and/or (b) deactivate or cancel your account if: (i) we are so required by applicable law, a facially valid subpoena, court order, or binding order of a government authority; (ii) we reasonably suspect you have or may act in violation of this Agreement; (iii) use of your account is subject to any pending litigation, investigation, or government proceeding and/or we perceive a heightened risk of legal or regulatory non-compliance associated with your account activity; (iv) our service partners are unable to support your use; (v) you take any action that we deem as circumventing our controls and procedures or (vi) we think it is necessary to do so to protect us, our users, including you, or our employees from danger or loss. If we exercise our rights to limit or refuse your access to the Services, we will not be responsible for any consequences of our refusal to give you access to the Services, including any delay, damage or inconvenience you may suffer as a result...
If you are holding bitcoin in your Paxful Wallet and there has been no activity in your account for a period of time prescribed by applicable law, we may be required to report such remaining bitcoin in your account as unclaimed property in accordance with abandoned property and escheat laws. If this occurs, we will use reasonable efforts to provide written notice to you. If you fail to respond to any such notice within seven (7) business days of receipt, or as otherwise required by law, we may be required to deliver any such bitcoin to the applicable jurisdiction as unclaimed property. We reserve the right to deduct a dormancy fee or other administrative charges from such unclaimed bitcoin as permitted by applicable law.
In other words, they can do whatever they want according to their rules, and they don't even have to give you any explanation. They seem to think that you have broken some of their rules, and for now they obviously do not intend to change their decision. If you can afford some legal help (lawyer or legal adviser) that would be best.
What you can do on this forum (if you consider yourself cheated) is to open a
Scam Accusations and to present all the evidence by using proper report format. Maybe Paxful will react to that, of course if you let them know.
Maybe, on the contrary, he was too upset and decided to delete everything related to cryptocurrency and left the forum too? 
