So I use my stepsister's old account, and she says that she didn't change the password. I know for a fact I have been putting in the correct password and email. I have also tried the username, and it didn't work. And we don't know the password to the email account, so is there anything I can do to get on it? And she doesn't know the security questions either (she is very disorganized and loses things.) Please Help Thanks!
Please contact Mojang support with your transaction ID. For more info visit https://help.mojang.com/customer/en/portal/articles/329524-change-or-forgot-password
Contact them, they're really helpful. Even if you can't find the transaction ID, they can probably verify your identify and help you.