ORA-27101 ORACLE Not available

Problem Description : Open plsql Today, error does not recognize the connection service

1. Then go to find out if the Oracle service did not start, but found that Oracle's other services can be started. Only oracledbconsolearies cannot be started, which means that there are some problems with Oracle's operation. 2. So I thought, If Oracle itself does not start, then sqlplus to start Oracle Error: Oracle not available ORA-27101, and ora-28056:writing Audit records to Windows EventLog Failed.3. So, do you think this is a failure to write to the Windows log? The Windows Event Log service is not started.Sure enough: Windows Event log does not start.Right-click to start: error WINDOW7:4201 Unable to identify the valid WMI data provider for the instance name that came up

4. Check the relevant information on the Internet, add the C:\windows\system32\logfiles\wmi\RTbackup permissions to the system, and give full Control permission.

5. Restart the computer, Windows Event log starts normally. Connect Plsql again, can connect oracle.oracledbconsolearies also can start. 

ORA-27101 ORACLE Not available