EDIT: I think I\'m close to solving this now. i will self-answer if so
I\'ve been stuck on this for a while now - I want to use the sample Oracle Human Resources databas
Good news - I finally figured it out. I had to go into SQL Command Line, and then put in these commands( from this link) :
Type: connect
Enter user-name: system
Enter password:
Then, we need to unlock the HR :
SQL> ALTER USER hr ACCOUNT UNLOCK;
Then we make a password for this user :
SQL> ALTER USER hr IDENTIFIED BY <hr-password>;
So after this, I could access it from SQL Develloper. thanks