If you start deleting contacts and make a mistake, don’t worry the information isn’t lost forever. Instead, it can be retrieved with the restore featured nestled in the Google Contacts menu.
Here’s where to find it:
From within the Contacts app
This will pop up a dialogue box enabling you to restore contacts from the past 30 days.
You can optionally choose:
Or enter a Custom date range
Note: you can use the export function to download your contacts into a CSV file as a backup prior to making significant changes.