Click on Reset Password on the login page and check your mail.
It could also be that your workspace was purged. I believe there is a maximum number of days for non-activity. If so, just request a new workspace.
I have not use my workspace for years, but
1. I did reset my password.
2. I am receiving regularly messages from APEX. I am applying not to purge my workspace.
I think the message is clear - the account is locked. It is same as from Oracle server.
In Oracle that account should be unlock automatically in 30 min. or as is set by DBA.