ORA-28056: Writing audit records to Windows Event Log failed

SQL> conn /as sysdba
ERROR:
ORA-28056: Writing audit records to Windows Event Log failed
ORA-28056: Writing audit records to Windows Event Log failed
SQL> startup
ORA-28056: Writing audit records to Windows Event Log failed
OSD-158714908: Message 158714908 not found;  product=RDBMS; facility=SOSD

O/S-Error: (OS 1502) The event log file is full.

This was because the Event Viewer log is full and could not log anymore events.
The solution is to clear the event log as follows Control Panel->Administrative Tools->Event Viewer->Clear All Events

Now connect Your Database.
SQL> conn /as sysdba
Connected.
SQL>