Question: Even if the backlight isn't on, can you see, if you get the lighting right, any kind of display?
The backlight is a cold-cathide flourescent tube, which is driven by an inverter, which provides the high voltages for the backlight.
The inverter is usually a long, thin circuit board inside the display part of the laptop case.
If you can see a faint, unlit picture on the screen when the laptop is on, it's probably the inverter that has failed, though there's an outside chance it is the cold cathode tube itself.
The good-ish news is tha tome Toshiba laptops were recognised by Toshiba as having a problem with the inverter and Toshiba did replace many inverters free of charge, even if the laptop was out of warranty.
The bad news is I can't find the reference so you'll need to do some in-depth and patient Googling.
Repairing yourself isn't too difficult, so long as you are patient, methodical and careful. Check this site as typical of the process:
http://www.laptoprepair101.com/laptop/2007/01/31/replace-screen-inverter-fix-backlight/comment-page-16/
I'll post again if I do find any reference to the Toshiba program.
John
May 2008