Unknown Issue

Hello hello! I'm having some new problem with my 1.5 years old laptop computer. It's an HP Pavilion dv9500 running Windows Vista with the same hardware it had when it came out of its box.
I'm not sure what happened to it. Everything was fine until I walked away for a short while and when I came back the display was completely black. It was still on but the system was completely unresponsive. I attempted to kill the power. When I turned it back on, the display appeared to activate but there is still no visible output. There appears to be some activity taking place, yet nothing shows up on screen. I suspect something may have burned out, but I have no clue.
Can someone help me determine the problem? Thanks!

It sounds like the power inverter or backlight has failed.
T%urn it on & let it "start" .
Take a flashlight ["torch" if you're in the UK] & shine it on the screen.
If you can see a faint disply then one of the 2 above has failed.

If you can not see any thing on the screen the video adapter may have failed.

All right, I started it again. The backlight appears to flash on but still nothing is displayed. In fact, I just heard Vista boot normally - which wasn't happening until now. Is there anything I can do or anything I should try before I start replacing things?