If you synced your contacts to iCloud, and your contacts still kept in iCloud backup files, you can restore iPhone contacts as follow steps.

Step 1: Launch the Settings app on your iPhone or iPad.
Step 2: Tap on iCloud.
Step 3: Turn on the option for Contacts �� if it��s already on, turn it off and then back on again to trigger a re-download. When asked what to do with existing contacts, choose the Delete option.
Step 4: If you are asked, choose to ��Merge�� contacts.
Step 5: Launch the Contacts app or the Phone app and verify your contacts are all there.

Tips: please make sure the synchronous is turn off while you are restoring contacts in case the files in iCloud are deleted. So we recommend an mobiletransf other guide for you.

The safer guide for you as follows:

Step 1: login https://www.icloud.com/ with your Apple ID, if you have two-factor authentication turned on, you��ll need a trusted device to generate a code to log into iCloud and access the settings.

Step 2: choose ��Contacts�� to check the lost contacts
iCloud options for recovery iPhone Data

Step 3: if your iCloud contacts still exists. Selected the one, and choose Export vCard to save your contacts to computer. iCloud also provides the ��Select all�� option, it��s helpful to backup all contacts very.
iCloud-iPhone_contacts_recovery_options_s
If your contacts did not exist here, use iphone transfer the iCloud advanced function.

Step 4: Choose ��Settings�� at iCloud home page
iCloud Settings

Step 5: Roll down to the ��Advanced��
iCloud recovery advanced settings for contacts

Step 6: Choose ��Restore contacts��. Tips, there are some other functions to help iPhone users restore iPhone files data, calendars, reminders, bookmarks, etc.
restore contacts form iCloud

Step 7: iCloud will ask you to select an archive of contact to restore, choose the right one, and repeat step 1, 2, 3 to backup iPhone contacts.

Notes: for using iCloud advanced restore function, please notice that, the archive of contacts you select will replace contacts on all your devices if you turned on iCloud synchronous on your iPhone. And your current contacts will be achieved for you may need these file back.