What to do in case of ora-12543: tns:destination host unreachable?

If you see the ora-12543: tns:destination host unreachable, you should follow the below steps:

1) we have to login to the sqlplus in the command prompt and connect as sysdba

sql>connect /as sysdba;2 ) alter the sys and unlock the account.

ALTER USER sys IDENTIFIED BY [newpassword] ACCOUNT UNLOCK;

  3 ) you can login via following url :https://localhost:5500/em

  4 ) Enter the username as sys and new newpassword<br>

5 ) you can able login as sys account and continue with your dba works