One of my students, who I am proud to say is using Ubuntu, kinda made a mistake.  He was experimenting with the video cable to get his computer to either run on the tv or to get the computer to play tv...I am not sure which. Anyway, using the s video cable he hooked the laptop to the tv and changed the setting through the GNOME GUI to accept the tv as the main monitor.  Now, the screen is blank and only boots when the video cable is hooked up to his laptop.  He is on another student's laptop downloading and burning a copy of ubuntu so he can run it live.  Once he gets in, I have NO CLUE what to tell him to enter to change the monitor video settings back to the laptop screen...thoughts? Thank you in advance.