changes to contact disappearing on iphone

1. Is this your corporate/organization/enterprise/School Management iPhone? Then please contact the system administrator of your corporate//organisation/enterprise/School Management
2. If it is your device, in that case, do you have any profile installed by your corporate/organization/enterprise/School Management?
   1. Erase the profile added by you. If you have installed a profile on your own, --> Install or remove configuration profiles on iPhone - Apple ...
   2. Please contact the system administrator of the organization who provided the profile to you

If you are unable to find your contacts that were stored on iCloud, then try this --> Restore contacts, calendars, bookmarks, and more using ...

Check if the email account has been removed from the iOS mail app.

Add the email account that stores your contacts in the IOS mail app and enable Contacts.

What is your default Contacts account?

Unlike some Android devices, contacts are neither stored locally on an iPhone nor in the SIM. They are synced to an email account that you have Google, iCloud, AOL, Exchange, Outlook, Yahoo, or any Other