I'll help you restore your account to its former state in QuickBooks Self-Employed.
Are you referring to the deleted connected bank account in Self-Employed? When a bank account is deleted or removed from your account, we're unable to restore it to its former state.
Though if the account has been inactive for more than a year, it may have been deleted already. When an account is canceled or if you haven't re-subscribed, the system will still keep your data for a year. After that, it will automatically be removed from our records.
We'll want to create a new Self-Employed account, then re-categorize the transactions if you still need to manage your estimated taxes.