Have you been overrun by spam comments? All too often I see sites that have hundreds of comments pending, all of them spam.
The first step to getting your comments back under control is bulk deleting all these unwanted spam comments. Within WordPress, you are limited in how many you can delete at once so you need a plugin that will bulk delete. I suggest: https://wordpress.org/plugins/wp-bulk-delete/
With the plugin settings, you can select to remove all pending comments and in one click get control of your comments.