As you can see from the purchase receipt we sent you with the activation key, we suggested to make a backup of the installer in a safe place, because it won't be available forever on Digital River.
"Safe place" doesn't mean the main PC drive because, as you can see, hard drives can crash, that's why backups should be made on a different media ( or a cloud drive ). Please contact support by EMAIL with your proof of purchase (order number), and we'll instruct you how to get another copy of the installer.