Go to iforgot.apple.com to reset your Apple ID password.:
If you forget your Apple ID password or simply want to change to a new one, use Safari on your computer or any of your devices to go to iforgot.apple.com where you can enter your Apple ID and begin the process. You'll be asked to choose whether you want to confirm your identity via an email to the account associated with your Apple ID or by answering the security question you put in place when you first created it. As you create your new password, you'll see an indication of its relative strength in the area below the form. You can keep entering and editing until you achieve your ideal password strength. When you're satisfied, confirm your password and tap or click the Reset button.
You can use your Apple ID in iTunes, iChat, iCloud, the Apple Online Store, Apple Retail Stores and at Apple.com Support. If you don't have an Apple ID and want to create one, go to appleid.apple.com.