Windows Ora-12560:tns: Problem with protocol adapter error

Windows Ora-12560:tns: Problem with protocol adapter error
There are three reasons:
1. The monitoring service is not up. Windows platform: Start---program---management tools---services, open the Services panel, start the Oraclehome92tnslistener service.
2.database instance did not rise up. The Windows platform: start---program---management tools---services, open the Services panel, start oracleservicexxxx,xxxx is your database SID.
3. registry issues. Regedit and then go to HKEY_LOCAL_MACHINE\SOFTWARE\ORACLE\HOME0 set the environment variable ORACLE_SID to XXXX,XXXX is your database Sid. Or right My Computer, attribute--advanced--environment variable---system variable--new, variable name =oracle_sid, variable value =xxxx,xxxx is your database SID. Or enter Sqlplus before you lose at command line. set oracle_sid=xxxx, XXXX is your database SID.

Windows Ora-12560:tns: Problem with protocol adapter error