Okay, so our school gave everybody a Gmail account, and everybody "chatted" on it when we were supposed to be working. One day we went on gmail and everybody's chat is gone completely. We all think its the School that went into our accounts and turned it off. So my question is, How do you turn it back on?!
If your school uses a private domain name (i.e., your email address does not end with @gmail.com) then the administrator controls access to any and all features of your account, including Google applications such as chat. There's nothing you can do then. Just switch to your own GMail account, or use an external app to chat.