I received a mail from my customer. He wants a refund. What should I do next?

I am new to Envato. This is my 7th sale and after that I received a mail from my customer. He wants a refund. What should I do next?

Why he want to refund ?
Is he download your item ? if he download your item then he don’t deserve refund. Envato market have some rules about refund.

I don’t know how to check whether the item has been downloaded or not

check his refund request details
Check my screenshot = http://prntscr.com/sl6qcz

you will not be able to check untill they will request for refund from the envato market refund page. do you know why they asked you refund through email? if don’t know then ask them. why they ask for refund it is most important.