404 error while in dashboard

404 error happened while in dashboard i was updating option menu with additional information. now i cannot access to admin site, its stating 404 error. in the front end has been messed up.
front end http://www.accountantclub.co.uk/index.php/
admin end http://www.accountantclub.co.uk/index.php/wp-login.php?redirect_to=%2Fwp-admin%2Findex.php

please somebody help me