Drupal – Whole backend 404


My whole entire Drupal admin system seems to have a 404 error problem.

http://www.mysite.com/user brings through the frontpage panel and lets me login (within the skin of the website) which is fine.

http://www.mysite.com/admin and ANY other path which would bring through the Drupal install turns into a drupalised (is this a word?) 404. There has been no change in any htaccess files.

Any ideas what this could be?


Drupal version: 

Source: https://www.drupal.org/taxonomy/term/22/feed