If you have purchased a disk, Magic Mouse will replace it free within twelve months from the purchase date if it should cease to read cleanly. To obtain a replacement cd, mail the defective disk to Magic Mouse. After the twelve month period, you will need to order a replacement CD. Replacement CD's are $10 delivered. To order a replacement CD, please send by phone, fax, or email a description of the product, platform, and version number of the product you are replacing.