Ivy here from Shopify.
Customer accounts can be viewed and ,managed right from your store's admin
It may be possible for our escalated technical support team to recover a deleted customer's information for you, I have seen this done before - however - we cannot revert a deleted customer's account. So we can get the customer data for you to be able to re-create new profiles for these deleted customers, but can’t revert the deletion so they go back to the exact same state they were in prior to deletion. In order to request this, you would have to reach out and create a support ticket request via our Shopify Support Portal.