The WP_users table appeared to be hacked and the role and the nicenames were all altered. These have now all been corrected in phpadmin, but if 'users' is clicked in the dashboard it states that there are over 28 000 anonymous users! The total of all users in phpadmin is only 606.
On the dashboard if you click on anonymous it appears that in fact there are only 154 anonymous users, all of whom are actually members. How can I correct these anomalies?