404 Messages on Plugins, and Updates

Hi,

We have been experiencing 404 messages whenever we try to update, or make changes to our plugins. We turned off every single plugin, and went about the process of activating them individually. From there we encountered plugins that once worked now showing errors. We spoke with our theme provider, and they updated the theme. We have spoken, and worked with our hosting provider. Who made changes where they needed to, but we are still getting issues. We even tried going back to last wordpress before the current update. What are the solutions, and what are we missing? The website is https://www.Thekingslayer.com. Any, and all help is greatly appreciated.

Thank you