There could be many reasons for this. More information is needed. Did you delete all the files before upgrading? Was your upgrade from an older version of WordPress or a more recent one? Did you follow all the instructions during the upgrade or install? Were you upgrading or installing when the error happened? Or after installing a Plugin? Did it just come out of the blue? Have you checked to see if your host changed anything or upgraded WordPress? Have you checked to see if your site has been hacked (if you are running an older version of WordPress)?
Without more specifics as to what you did to lead up to this moment, it’s rather difficult to help.
The file dissapeared so I uploaded a new wp admin I think what I need to do is give some information somewhere but where?
