In the past if you deleted contacts in Gmail they were lost permanently after a short time. No more, because now Gmail allows you to restore your contact list to an earlier date. This new feature allows you to undo deleting a contact, undo importing contact, or undo a contact list merge.
We’ve added a new feature to Google Contacts that allows you to revert your contact list and undo any mistakes made up to 30 days in the past. Let’s say you accidentally deleted a bunch of contacts or wiped the contact data from your Gmail account by mistake while syncing to another device. Visit Gmail’s Contacts section, select “Restore contacts” in the “More actions” menu, and choose the time you would like to revert to.
– From the Gmail blog, Restore Your Contacts