Why I can't view the documentation the old way?

If your talking about the older CodeIgniter Documentation you can get the files from
the CodeIgniter 2.2.6 build.

SEE: Writing Documentation in the CI 2.2.6 Users Guide you can get the original files
from there.

What did you Try? What did you Get? What did you Expect?

Joined CodeIgniter Community 2009.  ( Skype: insitfx )