Friends Changed My Gamertag To Something Vulgar.

Sadly it is your profile, which means you have the sole responsibility for others actions which includes changes to your gamertag. As my colleagues have mentioned; either put your gamertag in as a nickname (I've seen some gamers write it in their bios),
or you have to pay the money to have it changed back to how it was before (provided no one has snagged it in the meantime). Best of luck!

- Shandy

I'd just like to point out that on the Enforcement website it basically says you are ultimately responsible for what happens on your account. There is a section about suspensions, but it would apply to Gamertag changes too.

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/home/howto#sub-topic0-5

You'll have to pay to change it. Having positive control of your account is part of the TOS

Hello,

I myself encountered this problem some time ago, it is quite possible to write your old pseudonym in the change of gamertag and it will pass for free normally unless you have received a suspension, in
this case I was waiting for the suspension to end before trying the methods I gave you.

Thank,

Unfortunately you will not be able to change it back to your previous gamertag. You will need to change it to a new gamertag, unfortunately you will need to pay for the new gamertag.