What to Do if a Plugin Kills Your WordPress Site
Most of the time if a plugin has broken your site, you won’t be able to get into the admin area to deactivate it. The simplest and easiest way to get your site back online is to rename the offending plugin’s folder. For example, if the plugin that broke your site is called “MyEvents”, you can rename it to “MyEvents-2”. Then you can decide if you want to delete the plugin, use an older version, or find a way to fix it.
For a guide to best practices when installing and upgrading plugins, check out our recent article: Think Twice Before You Upgrade That WordPress Plugin