Oracle Database Discussions

Hi all,
I have this message "ORA-01012: not logged on" when I want to log on Database.
I try to shutdown and start database, but nothing, others errors messages.
SQL> startup
ORA-01081: cannot start already-running ORACLE - shut it down first
SQL> shutdown immediate
ORA-24324: service handle not initialized
ORA-24323: value not allowed
ORA-00020: maximum number of processes (%s) exceeded
SQL> shutdown immediate
ORA-24324: service handle not initialized
ORA-24323: value not allowed
ORA-00020: maximum number of processes (%s) exceeded
SQL> shutdown abort;
ORA-01031: insufficient privileges
SQL> shutdown abort;

Thanks a lot for your help.