I just learned the very hard way that Zoho will independently delete
any reports from CRM analytics, if a user will remove a field (in From setup) that is used in these reports.
Zoho does not provide any alert to the users that removing a field from their form layout, will cause a permanent and irreversible deletion of their advanced analytic reports.
Zoho does not have the feature to back up Advanced reports, as well as restore them.
Please be aware of this shortfall, as this now cost my company almost 200 hours of customized work, that is now gone.