Check the Contacts app and search for the missing contact
Open Phone or Contacts and look in Favorites, Recents, or Groups
Turn on Contacts in iCloud: Settings > [your name] > iCloud > Contacts
Sign in to iCloud.com and restore contacts from an earlier archive
Restore contacts from an iCloud backup
Restore contacts from a computer backup using Finder or iTunes
Check Gmail, Outlook, or other synced accounts for the contact
Re-add the contact manually if you have the phone number or email
Ask the contact to share their contact card again
Check Messages, Mail, and call history for saved contact details
Use a third-party data recovery tool if no backup is available