You will have to guess until you get it correct, or you can just make a new backup and start fresh, unless you are on a Mac. See the instructions below.
iOS: Troubleshooting encrypted backups
When you restore from a backup in iTunes, you may be asked for a password to unlock the backup. Learn what to do if you can't remember or do not know your backup password.
One of these situations may apply:
- Backup encryption was enabled, but you do not know the password
- An administrator installed a profile on your device that requires backup encryption
You can keep trying to restore the device from backup until you remember the password. If you're having trouble, try:
- Leaving the password field blank
- Your Apple ID password
- Your computer account password, if you have one
- Email passwords you may have used
- Your Wi-Fi network password
- Website passwords you may have used
- A password for hard-disk encryption software, if you use it
If you have ever had a VPN connection or an Exchange email account set up on your iOS device, try using the password associated with those accounts. If you have changed your password for that account in the past, try using an old password. If that doesn’t work, contact the administrator for the account and see if they have a default password enabled on the account.
Profiles are common when the device is part of an enterprise deployment and may be required for Exchange, VPN, or internal security. Administrators make iOS Profiles using the iPhone Configuration Utility or Apple Configurator. Profiles may enforce backup encryption. The first time your device syncs after such a profile is installed, you must enter a backup password. In some cases, an administrator may have synced the device for you and entered the backup password then. If so, ask the administrator who issued the device to you for the backup password.
If you are using OS X, the password might be saved in Keychain Access. Follow these steps to see if this is the case:
- Open iTunes Preferences and select the Devices tab. Note the time of the device’s backup.
- Right-click the desired backup and choose "Show in Finder".
- Finder should now be open, showing the backup selected. Click the Edit menu and choose Copy.
- Open Keychain Access from /Applications/Utilities/.
- Paste the backup folder's name into the search box in the top-right corner of Keychain Access.
- If there is a password for the backup, you should see it in Keychain Access.
- Double-click the backup in Keychain Access.
- Click the button “Show password”.
- You may be asked to enter your login keychain password. After doing so, click Allow. You should see your backup password.
- Use this password to restore from your backup.
I can't recall my encrypted password for my back up. How do I remove the password?
See iTunes and encrypted backups here > http://support.apple.com/kb/HT4946
If you cannot remember the password you will not be able to restore the backup