Issue With Administrators Manage

Since I created new admin today, all other admins disappeared on list? Only one admin (last one) is visible and I can't delete it. Error (Sorry, user with prefix 6 can't be deleted) When I try to register my first admin (super admin) it said that email is already registred, but didn't show at administrators list. I can't manage languages, what is happening? Sorry on my bad English

Looks like you are logged in under the new administrator account. Therefore other administrator accounts are not visible. Please try to login under the root administrator in another browser.