Gmail allow restore of contacts up to 30 days

If you make changes to your contacts that you want to undo, you can restore your full contacts list to an earlier saved version. This allows you to undo changes like:

• Recovering contacts that have been accidentally deleted
• Restoring contacts after an unsuccessful sync
• Undoing a recent import
• Undoing a recent merge

Restore Google Contacts up to 30 days

To restore your contacts to a previous version, just follow these steps:

1. Click Contacts.
2. From the More actions drop-down menu, choose Restore contacts.
3. Choose the time you'd like to revert your contacts list to (e.g. 10 minutes ago, one hour ago, one week ago, etc). We suggest that you also make a note of the time that you restore your contacts, in case you'd like to return to where you started.
4. Click Restore. You'll see a confirmation at the top of the screen when the rollback is complete.

To undo a restoration:

• When the operation completes, a notification bar will appear that gives you the opportunity to immediately undo the restore. This notification bar will disappear if you leave Contacts or make edits to your contacts.
• If the notification bar is no longer there, you can always re-run the Restore Contacts tool to take you back to where you started. Just set the tool to take you to the time just before you started the whole process.

The 24 hour rule for Chat contacts:

When you delete a contact in Contacts, it will also get deleted from your Chat list. After the contact is deleted, Chat still remembers the invitation status for that contact for another 24 hours. So if you restore a deleted contact within 24 hours, it will be fully restored in Chat. But if you restore a deleted contact after 24 hours, you'll need to re-invite that person to your Chat list.

Restore contacts [via]