To restore a deleted customer follow these steps:
Click 'My Customers' at the top of your screen to open the customer database.
Click on the '...' icon and choose 'Restore deleted customers' from the drop down menu.
This will bring you to a list of all of your deleted customers. Click the blue 'restore' button to the right of the contact you would like to recover. When all the needed customers are restored, click 'ok' in the bottom right.
You'll be taken back to the customer database with the restored customer's information added back to the list!