It happens frequently that customers forget their passwords, and try too many times to login.  Too many incorrect attempts and CFWebstore will lock the user account.  In order to unlock the account, go to the admin section and go to USERS > USERS > (search for users login account).  Click 'EDIT'.  Go to the bottom of the screen and look for 'RESET LAST DAY'.  Change the radio button to 'YES' and hit 'SUBMIT'.  This will reset the users account and allow them to try logging in again. 

NOTE:  The user may not remember their password, and so if you reset the account and they try the wrong password again a few times, the system will lock them out again.  If they are unsure about their password, still execute the above process, but before hitting submit, enter a new password for their account and send it to them via email.