I had the same error, however my fix was slightly different. In my .htaccess file, I had the following line already in there:
AddHandler application/x-httpd-php52 .php .php5 .php4 .php3
Looks like things were set up for PHP 5.2, but this causes the 404 error for me. By getting rid of the pesky “2”, suddenly things worked:
AddHandler application/x-httpd-php5 .php .php5 .php4 .php3
Not sure if this will help you, but gilmansean certainly pointed me in the right direction.
Quick note for those using Cpanel file manager – be sure to click the “show hidden files” option in file manager or you won’t see the .htaccess file. Once I checked the option, I was able to get into the file and use the file manager “edit” option to fix things. Before I paid attention and clicked the “show hidden files” option, I was a wee bit confused…
