Q: i've lost all my contacts in my iphone

Greetings, Sapphire Blk. Thanks for joining Apple Support Communities.

It appears that your Contacts have disappeared from your iPhone. Since I haven't memorized a phone number in years, I'd be lost without mine. I'll be glad to help.

iPhone: Add contacts -- This link shows you the many different ways you can use and sync your Contacts. There are many ways to add contacts to your iPhone so it will depend on which method you used to determine whether or not you can restore them. Many people use iCloud to sync their contacts across devices though, so I'll focus on that. If you're not using iCloud, let me know how you added contacts to your iPhone, please?

Get help using iCloud Contacts, Calendars, or Reminders -- If you were syncing your contacts to iCloud, log into the website from a browser on your computer using this link: Sign into iCloud -- click on the Contacts link to see what you find there.

iCloud: Restore your contacts, calendars and reminders, or bookmarks -- If you were using iCloud to sync your contacts, you may be able to restore them with help from this article.

Restore your iPhone, iPad, or iPod touch from a backup -- If you were not using iCloud or another syncing service, you would need to rely on backup in either iTunes or iCloud. This would erase the content that is currently on your iPhone and replace it with the contents of your backup.

Take care!