It is easy to regain deleted contacts from iTunes Backup, following steps are useful:
1) Run FoneLab on your computer.
2) Click Recover from iTunes Backup File. If your device has been backed up with iTunes before, it will be in the list.
3) Check the iTunes backup file and start to scan. After scanning, all files will show up. Select the required contacts' information under Contacts category in the list.
4) Click Recover button to start the recovery.