File type returning NULL - Did actually work but I don't know what I have done. Help!

Uploaded files handle differently from uploaded form data.

You have form_open_multipart function call followed by another form tag, that will generate two forms inside each other and submit will only work in inner form, so that might cause some issues.

Also, all type="file" go into $_FILES instead of $_POST variable.

More details on how to handle uploads with CodeIgniter at https://www.codeigniter.com/userguide3/l...ading.html
Also, for raw PHP approach, you can read up how it works here http://php.net/manual/en/features.file-u...method.php