Which wallet were you using and to which VPN did you send the coins to?
Try contacting BitPay with the transaction ID (you can get that from your wallet) and the deposit address you sent the coins to (you can also get that from your wallet).
He has no transaction ID because his balance disappeared after he did the transaction. There might be a bug happening,
There is no way you can recover it by yourself, try to contact the support and explain your problem with them.
Try to reach them by using this form
https://bitpay.com/request-help/wizard, choose BitPay Payment and then fill the forms.