An account on Zimbra can become locked if someone is running a dictionary attack against it. More than 10 wrong password attempts in an hour will lock it for about an hour (I think those are the defaults).

Unlock an account from the command line:
zmprov ma  zimbraAccountStatus active
Fixing logger not starting

 Change webmail port

su - zimbra
zmprov ms zimbraMailPort 8888
zmprov ms zimbraMailSSLPort 8889
zmcontrol stop ; zmcontrol start