My iPhone was stolen how do I get my contacts

If you weren't syncing contacts to iCloud, you can restore another device using a backup from the device you lost.

Restoring from a backup erases all data currently on your device. Any data newer than when the backup was made will be erased. A restore is an all or nothing restore.

Backup - Restore your device from an iCloud or iTunes backup

If you have before the lost in Settings > [your name] > iCloud > Contacts : ON

you can use a computer browser with this link: https://www.icloud.com/#contacts