Account banned from someone else playing on it

to see about submitting a case review, you would need to go to
http://enforcement.xbox.com However, you are responsible for your account at all times. So it doesn't matter if it was you or your family member. If it was done on your account, your account gets the suspension.

i already did that and they said since it has been done to the account that i cant get it lifted. Now if someone broke into my house and somehow got into my safe and stole my gun and killed someone is it the persons fault that stole it and killed someone
or is it the guns fault that it killed someone? Or am i to blame because it was stolen and used to kill someone?

https://enforcement.xbox.com/en-US/home/howto#sub-topic0-5
My roommate was playing when I got suspended. Can it be lifted?
Xbox Live is a social platform, and we love hearing about players sharing their experience with friends and family. Xbox Live is at its best when everyone joins in the fun!

However, as the owner of the account you are ultimately responsible for how the account is used, both good and bad. When we issue a suspension, it’s not necessarily because you committed a violation, but because the account was used to commit a violation.
Even if you weren’t home or holding the controller when the activity occurred, if a particular Gamertag was used to harass other players or cheated in a game we have to hold it accountable.

If you wish to restrict usage of your account you can set up a passkey on

Xbox 360 or
Xbox One. And thanks to the benefits of
Home Gold, it’s easier than ever for every member of the household to create their own Xbox Live account!

https://enforcement.xbox.com/en-US/home/howto#sub-topic0-5
My roommate was playing when I got suspended. Can it be lifted?
Xbox Live is a social platform, and we love hearing about players sharing their experience with friends and family. Xbox Live is at its best when everyone joins in the fun!

However, as the owner of the account you are ultimately responsible for how the account is used, both good and bad. When we issue a suspension, it’s not necessarily because you committed a violation, but because the account was used to commit a violation.
Even if you weren’t home or holding the controller when the activity occurred, if a particular Gamertag was used to harass other players or cheated in a game we have to hold it accountable.

If you wish to restrict usage of your account you can set up a passkey on

Xbox 360 or
Xbox One. And thanks to the benefits of
Home Gold, it’s easier than ever for every member of the household to create their own Xbox Live account!

if someone broke into my house and somehow got into my safe and stole my gun and killed someone is it the persons fault that stole it and killed someone or is it the guns fault that it killed someone? Or am i to blame because it wa stolen and used to kill
someone?

to see about submitting a case review, you would need to go to
http://enforcement.xbox.com However, you are responsible for your account at all times. So it doesn't matter if it was you or your family member. If it was done on your account, your account gets the suspension.

i already did that and they said since it has been done to the account that i cant get it lifted. Now if someone broke into my house and somehow got into my safe and stole my gun and killed someone is it the persons fault that stole it and killed someone
or is it the guns fault that it killed someone? Or am i to blame because it wa stolen and used to kill someone? this is just an anology my profile being the gun the family member being the person breaking into the house

to see about submitting a case review, you would need to go to
http://enforcement.xbox.com However, you are responsible for your account at all times. So it doesn't matter if it was you or your family member. If it was done on your account, your account gets the suspension.