At least send him an email or two to make it look like you tried to communicate with him. Then, Paypal dispute (assuming you used Paypal).

If he sent you something other than you ordered and refuses to refund you or cover return shipping and give you the correct order, Paypal will side with you. I've had a vendor tell me they sent me something twice, but I never got anything after waiting for 2 months. Paypal got my back.