trouble starting up acer laptop

[violetiris]

I have a one year old acer aspire 4730z laptop(vista) and today when I turned it on, the acer screen showed up (as usual) and then the green sliding bar showed up (as usual) but then it would either freeze on that screen, or after a couple minutes, the screen would go black. i was able to get to the vista log in screen but then it restarted itself.
It was working perfectly fine the night before, and I have a lot of important information on there. Is there anything I can do to fix this asap?
could it be a virus? or just a sudden error?
i don't know if this has anything to do with it, but my mom slammed the lid of the laptop shut with A LOT of force the day before my laptop broke (not sure if that did anything..probably not?)
any help would be great, thanks
-Iris
PS- feel free to "dumb things down"
i don't know much(barely anything) about laptops/computers
but ive been able to fix two other problems with this laptop before, though none as serious as this

[Wiro]

As you are not able to boot both the operating system, it could be because of the hard drive failure. If you can remove the hard drive of the laptop and check it by connecting it to some other computer, then it would be good. See if the hard drive gets detected by the other computer. If detected, download hard drive diagnostic tools and run it on the hard drive. See if there are any error.