This happens if too many incorrect passwords are entered in a row. During that time, you will not be able to log in or reset your password. Contact support for assistance or wait 15 minutes until the account is unlocked automatically.
If you have not entered the incorrect passwords yourself, it may be that someone is trying to guess your password, or that a user mistyped their e-mail address (writing yours instead). You should notify the helpdesk if you suspect this!