title: Error ORA-01034: ORACLE not available and ORA-27101: shared memory realm does not exist when trying to log in as system
body: <p>I am completely new at SQL plus. I forgot what I did during the class but now I want to try again by watching back the videos. I cannot login as system even after I changed the password by logging in using conn /as sysdba and alter user system identified by password;</p>
  <p>what should I do?
  <a href="https://i.stack.imgur.com/ouE72.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/ouE72.png" alt="enter image description here" /></a></p>
  <p><em>Update</em>
  I also made sure that the services are up. It's already up when I asked this question.
  <a href="https://i.stack.imgur.com/1H4vU.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/1H4vU.png" alt="enter image description here" /></a></p>