Fix Enter the Password to Unlock your iPhone Backup Error

Question

Hello dear iPhone Help community. I own a iPhone 6 and I'm the first owner of the device. Before a week I created a backup via iTunes, and today I restored my phone with the new iOS version. Now when I tried to restore my iPhone from the created backup, I got a popup message: Enter the Password to Unlock your iPhone Backup asking for backup password.

Here's What I tried:

1. I entered my Apple ID password, but it was not accepted.
2. Tried backup extractor, but still ask for password.
3. Disabled the encrypted backup from the settings.

Here's the screenshot from the iTunes error page:

 

 

Can you help me to fix this problem? I don't want to lose my data. I have very important data in the backup file.

 

Thanks,

 

Stephan.