Hi. This may be a plugin or theme conflict. Please attempt to disable all plugins, and use one of the default (Twenty*) themes. If the problem goes away, enable them one by one to identify the source of your troubles.
If you can install plugins, install and activate “Health Check”: https://wordpress.org/plugins/health-check/. It will add some additional features under Tools > Site Health, as well as a “Troubleshooting Mode” menu on the top bar.
Under Tools > Site Health > Troubleshooting, you can Enable Troubleshooting Mode. This will disable all plugins, switch to a standard WordPress theme (if available), allow you to turn your plugins on and off and switch between themes, without affecting normal visitors to your site. This allows you to test for various compatibility issues.
There’s a more detailed description about how to use the Health Check plugin and its Troubleshooting Mode at https://make.wordpress.org/support/handbook/appendix/troubleshooting-using-the-health-check/.
I know my theme coding has gone wrong and I have got the theme people that I brought it from working on the coding. Would this effect wordpress from saving or generating a preview?
I think yes, it’s possible that problems in the theme, or plugins, would affect previews.
Royal Themes told me that it is a plugin problem. Now I am getting a 404 error message and can’t login to my account at all but that is down to my hosting provider to fix so I can’t even do the staging site at the moment.
