My iPhone 13 pro max just deleted many important contact names and numbers. I need the back ASAP

Contacts on an iPhone sync to email accounts. If you have deleted or turned off any email accounts you may have deleted the associated contacts.

You may also just not be viewing them. Open Contacts. If you see Groups in the upper left corner tap on it and make sure all groups are checked.

If your contacts sync to iCloud see→iCloud: Restore contacts, calendars, and more in iCloud Settings