While building

Hi.
While building an estore, http://www.3m1concept.com.ng, I installed the W3 Total Cache plugin to speed up things but ended up breaking the site.

I quickly went to my cPanel and renamed the .htaccess file to .htaccessbak and then I renamed the plugin folder to disable the plugins. After doing this, the 500 error code disappeared only to be replaced with a 404. After trying to change the permalink structure(which was set to custom), the 404 error still persists.

Please I need your expert help to resolve this. Thanks