Sounds like they managed to get into the factory set up. On most sets, unplugging the TV and plugging it back in does the trick. If not, try leaving it unplugged for about four hours. If that doesn't work, contact a service center that works on that brand of TV and ask them how to disable the factory setup mode.
Post back here with whatever fix works for you to help others in the future that may also experience the same problem.
Sounds like they managed to get into the factory set up. On most sets, unplugging the TV and plugging it back in does the trick. If not, try leaving it unplugged for about four hours. If that doesn't work, contact a service center that works on that brand of TV and ask them how to disable the factory setup mode.
Post back here with whatever fix works for you to help others in the future that may also experience the same problem.