Oracle database 18c – ORA-12541: TNS:no listener
The error message clearly says there is no listener listening on the requested address.

Check if it is running (lsnrctl status), and start it if necessary (lsnrctl start). On Windows you will need to do this in a command prompt started with administrator privileges, because it also start a Windows service. Or you can start the Windows service called something similar to OracleOraDB18Home1TNSListener.