Vista - vista failure to start

hey
yesterday i was playing on my computer and my pc froze.
when i turned it on again it was asking if i want to repair the start-up files or just start, i selected just start and it took very long time loading the windows vista (the loading bar before the login) and when the bar was gone the computer screen turns blue for one second and it reboots.
after that i selected to repair the files, and after some time i got the mouse icon on the blue screen with nothing else.
what's my play here?
i'm really bad with computers so i guess it's better to take it to a store?

You're experiencing a blue screen of death. What you could do is determine the actual error code you're receiving. While booting up your computer try pressing (and holding) F8 which will bring you to a menu. Select Safe mode and check first if you can boot from there.

If successful you can access the event viewer which contains the error code. To do that, click on the start orb then type event viewer in the search box then press enter. I'm not quite sure but I think that that there should be a tree (+) beside the word critical. Click that and take note of the error code/s and post back here.

can't, trying to press f8 the computer start making very loud noise.
probably the best would be to format?

Formatting is the last option especially if you have data that you want saved. Do you have a recovery disc or installation DVD of your Vista Home Premium? If so, try the various repair options namely the startup repair option. A guide can be found here. This is tailored to your operating system.

thanks much, i had to buy a new hard disk because it was broken...
now i'm installing windows vista but i can't find my activation key... is there anywhere i could get one? the old one was written on the back of my laptop but it's impossible to read.

It's supposed to be somewhere on the DVD packaging. If it's not there and you're unable to read it from the PC, try calling your manufacturer about it.