Sorry to hear of the problem you are having.
It seems the issue of plugins that you installed.
Do you remember which plugin you have installed that caused this issue?
Also you can get more information about troubleshooting this issue on the following page.
These are not required plugins if you do not want to create e-commerce store on your site and display slider so it is not necessary to download them.
The plugins are standard plugins and thousands of users are using them without any issue so i don’t think they are causing this issue but may be other things as described on the post above.