How to restore contacts
I deleted my contacts and don’t know how to get them back in my phone
If you were syncing the contacts using iCloud, go to iCloud.com using a computer and select Settings. When that page loads, look at the bottom left side under Advanced and see if you can restore from there. If you weren't syncing with iCloud, restore from a backup.
How to Recover Files, Contacts, Calendars and Reminders in iCloud
Backup - Restore your device from an iCloud or iTunes backup