This worked for me:
How to deactivate all plugins when not able to access the administrative menus?
Sometimes it may be necessary to deactivate all plugins, but you can’t access the administrative menus to do so. One of two methods are available to deactivate all plugins.
Use phpMyAdmin to deactivate all plugins.
In the table wp_options, under the option_name column (field) find the active_plugins row
Change the option_value field to: a:0:{}
Or reset your plugins folder via FTP or the file manager provided in your host’s control panel. This method preserves plugin options but requires plugins be manually reactivated.
Via FTP or your host’s file manager, navigate to the wp-contents folder (directory)
Via FTP or your host’s file manager, rename the folder “plugins” to “plugins.hold”
Login to your WordPress administration plugins page (/wp-admin/plugins.php) – this will disable any plugin that is “missing”.
Via FTP or your host’s file manager, rename “plugins.hold” back to “plugins”
