Toshiba A200 Satellite running vista. Earlier this week the screen went black and sourced fix via tablet. Bought VGA cable and played through TV. Then wanted sound so bought HDMI cable. Could not get it to work so fiddled around and TV is now unsupported, too. Can't fix it as monitor screen is black and TV is unsupported.
1. Turn the laptop off (not sleep or hibernate but off).
2. Connect an external monitor to the laptop.
3. Turn on the external monitor.
4. Turn on the laptop.
NOTE: You may have to press an "external monitor" button. Could be the f4 button or a button with two monitors on it, for the external monitor to work.
If you can see fine on the external monitor, then your attached display, or the ribbon cable that connects it, are your problem.
If you can't see on the external monitor at all, or the problem occurs on the external monitor as well, then it is probably the graphics card/GPU that is the problem, which may require the motherboard be replaced.
If the reason the laptop's screen is blank were because its backlight failed, you might also be able to faintly see a small portion of what's displayed on the screen by holding a bright flashlight very close to it. That's obviously not practical for using the display on a regular basis, but might help you navigate some menus to possibly get an external screen working again.
Also, it's possible that the resolution might have changed to something that the television doesn't support, and you might just need to change it to something else.