Users Can't Log In
In the event that no user (including admins) can seem to log onto the web site, there is a possibility the 'sessions' database table has become corrupted. Though it appears the log-in process worked, it still shows no user logged in. This is true for all users, even the super-admin.
Fix: You must repair the "exponent_sessionticket" table. If you use phpMyadmin to manage your MySQL database, select the "exponent_sessionticket" table (with variations based on your specific database table prefix). In fact, it may display an error about the table being broken or corrupt when you select it. Next, click on the "Operations" tab at the top. On the next screen in the lower left are some "Table Maintenance" options and click on "Repair table."