How To Redirect People To The Correct Link?

[Olcho]

In my website some people arrives in a wrong link so they found the page 404 error (Page not found). I would like to know how can i redirect the people to the correct link.

 

Example:

• Wrong link: mysite.com/en/folder/folder/file.php
  
• Correct link: mysite.com/folder/folder/file.php
  

I need to know where and what php code i have to use, in order that, inside the page 404 (ONLY if the the link is present the string /en/ ) goes redirected to the correct link.

Thank you very much.

Olga.