Error editing database – lost plugins page display

I recently installed a plugin to beef up the security on my site bourne.gb.com and it prevented any of the back end pages from displaying. A bit panicked about how to regain access I went into the database and removed all fields associated with that plugin, and perhaps one more that I should not have done, and deleted the plugin itself from the folders.

This restored everything except the display of the plugins page. I get the page for adding new plugins, and the plugin edit page shows all plugins in that are installed. But I have no control over activation or deletion of plugins.

I recently updated to the latest WP version and am running a multisite installation. Can you tell me what field I might have inadvertently deleted and how I might reinstate it.