How would you deal with this dispute?

I was selling gold yesterday and I sold 50M gold for 35$ to one guy. Later that night he disputed it and the 35$ is being held.

How should I try to resolve this dispute? The four options PayPal gives me are...
- I have not shipped the item and I would like to refund the payment.
- I can provide proof that the item was shipped through an approved shipper to the address on the Transaction Details page.
- I have refunded the payment for this transaction.
- None of these apply to me.

What should I put for shipping address if it is a virtual good?

What best describes your transaction?
- Service
- Intangible Goods
- Buyer picked up the goods
- None of the above

Additional information:

 

I cannot provide proof (Unless you got screenshots)
And ring up paypal.