@ David,

I have a year old Dell laptop, and recently the graphics on the screen started slowly dimming, and then disappearing. Further the laptop starting failing to start, when I press the “on” button, and sometimes I would have to re-boot it more than 10 times, before starting.
Finally, it all together stopped working, and only a blank (white) screen appears. The fan works OK however.
Recently I was able to retrieve all the files in the hard disk, so I assume that the hard disc is fine. Is it possible to diagnose the problem form the information provided?

It’s hard to tell what’s going on but here’s what you can try.
You can disconnect the video cable from the LCD screen and test the laptop with an external monitor connected to the VGA port on the laptop. If the laptop works fine with the external monitor, most likely the laptop LCD screen failed (or the video cable failed). I suspect the screen failure.
I would try replacing the screen first. It shouldn’t be very expensive.
If the laptop doesn’t work with the external monitor, most likely this is motherboard failure.