Customizer Reset plugin will reset theme customizations made via WordPress Customizer by adding a Reset button in the Customizer. It's important to know when to use this plugin because if you don't have a backup of your customizer settings, you can not restore them at all.
You may need to use this plugin sometimes when you see the Customizer is not working properly. It could happen due to a plugin conflict or a corruption in the database. Almost all of the issues with Customizer will resolve as soon as you reset it with this plugin, but be advised that you need to reconfigure all the customizer settings after resetting your customizer.
The plugin details: