The return policy for digital items is a little different than physical.  Please see below for the specific digital return policy.

All digital items have a return time period of 10 days.  If it's been longer than 10 days since you purchased the item, it's unlikely that it can be refunded.  If it's been no longer than 2 weeks, reach out to see if there are any other options.

Access Codes: regardless of if the code is redeemed, once revealed, an access code can't be returned for a refund.  If the code is received with a physical book, the saran wrap can't be removed.  If a physical code alone, the code can't be revealed.

eBooks: these can be returned for a refund even if opened, as long as it's within the refund period time frame.  Also, more than 20% can't be accessed.  Scrolling through the book just to review what's there can affect the possibility of a refund.