Windows Vista Wont boot fully

I have a gateway laptop, 2 gb ram. I start up the computer and the windows loading bar appears and then the screen goes black and it stops loading. I tried putting it in safemode, also tried to repair the computer. It will just run until the windows loading bar is done. I dont have the Operating system cd and idk how to restore it without it fully loading. anyone have any idea? would the harddrive be fried and if so how do you know? if not is there a way i can restore it without it fully booting? I tried everything and im running out of ideas. please help

 

What did you try to repair it with? On boot up, do you get a recovery option on one of the F keys?