If the backup is corrupt you cannot recover your data. There are a couple of things you can try:
- Unless you have a Mac with Mojave or Catalina update to the latest version of iTunes from https://apple.com/itunes. If you have Windows use this link, do not get it from the Microsoft store
- Restart your computer
- Disable any antivirus software on your computer
If the problem persists after this there is no way to recover the backup. Most commonly this is caused by a sync or backup that was interrupted before it completed. Less common, but still possible, is a failing drive on your computer, or an attempt to manually edit or copy a backup.
Did you also make an iCloud backup? Or set up automatic nightly backups to iCloud? If you did either you can still recover from the iCloud backup.