Why doesn't "drush --debug en color" show any output? Running drush en color from the /xampp/htdocs/drupal directory doesn't output anything. The same happens with drush --debug en color. Why?
It seems that your drush installation is broken. So you have to reinstall it again.

The easiest way would be to install Composer and follow the instructions from drush-ops (especially check Windows section). Then check How to configure Drush on Windows 7?

If this is still happening, check your PATH environment variable if it contains the correct directories (maybe you have some non-drush binary within your system list of folders which could cause some conflict).