i lost all my contacts how do i restore them

You can extract your contacts from the iTunes backup when you lost your iPhone. iTunes can automatically back up your iPhone contacts and update it every time when you sync it. So you really have a big chance to recover contacts from iTunes backup.

If you don't synced, you can directly scan and recover deleted contacts from your iPhone.

Solution 1: Scan and extract iTunes backup to restore contacts on iPhone (without iPhone)

Step 1: Scan the backup file

Step 2: Recover your iPhone contacts

Solution 2: Directly scan and recover contacts from iPhone 5/4S/4/3GS

Step 1: Connect your iPhone to the computer

Step 2: Enter the device's scanning mode and scan it

1) Hold your device and click the "Start" button.

2) Pressing the "Power" and "Home" buttons at the same time for exact 10 seconds.

3) Then release the "Power" button, but keep holding "Home" for another 15 seconds until you get

Step 3: Preview and recover iPhone contacts