If the order is attached to your account, click on the Your purchases button from your user profile. On the purchases page, click on the Download button next to the item you want to download.
If the order is not attached to your account, go to the download resender tool and enter the email address used at checkout. The email address entered must be the exact email address used at checkout.
Note: Buyers registered with PayPal may have more than one email address associated with their PayPal accounts.
See also: How to attach orders to your account