If you added an email address to your user settings, you can use the Forgot Password link on the sign-in page to have a temporary password sent to you. If you don't have an email address included with your user details, then an administrator must reset your password. Contact your administrator to reset your password for you. Your administrator will give you a temporary password that is good for 7 days. If you do not use it in 7 days, the password will expire and you'll need to get your administrator to create a new one-time password for you.
If you are the default or tenant administrator for your site and you forgot your password, contact Oracle Support. For tips on filing a service request, see Getting Help and Contacting Support.