Can't return to admin area

I’m hoping someone can help. It seems I’m still logged in as I can see my admin toolbar
at the top of the site but when I try to get back inside the admin area at
http://warrensmaindomain.com/wp-admin it redirects to
http://warrensmaindomain.com/wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin%2Findex.php.
All the dashboard links redirect also, always starting with
http://warrensmaindomain.com/wp-admin/upgrade.php?_wp_http_referer=%2Fwp-admin% and file path with % and all
It seemed to happen after a one click wordpress update.
Hostgator support said it looked like I was missing a plugin at
/home1/wemarg/public_html/wp-content/plugins/wp-comcentral/
but that didn’t make much sense to me. Plus I never had that plugin installed.
The site shows up but has no sidebars anywhere. Any ideas? thanks in advance Warren