Ora-12514:tns: The listener currently does not recognize the service resolution requested in the connection descriptor

See if Oracle's monitoring and Oracle's services are all up first.

Start the Oracle listener: cmd command Line window, enter lsnrctl start, and the input will start monitoring.

To see what ORACLE's SID is called, such as when creating a database, the instance is named "Orcl", then manually set the Oralce sid,cmd Command window, set ORACLE_SID=ORCL

Re-enter Sqlplus/nolog, return

Re-enter Conn/as sysdba; Enter (or direct input sqlplus/as sysdba)

Then enter startup, enter. This step is to start the Oracle service. If startup is notified that it has been started, you can enter shutdown immediate first, and then enter startup after the shutdown is finished.

Ora-12514:tns: The listener currently does not recognize the service resolution requested in the connection descriptor