Windows vista won't start up?

Ok, i have an inspiron 1525 laptop. Today i had started it up well it froze on me and i had to restart it by holding the power button down. After 4 times of that, it suddenly stopped booting to windows. It advises me to pick startup repair, i do that but it won't do anything just asks the question again, so i pick normal mode and now it loads then i get a glimpse of the blue screen of death and it restarts, thats all its been doing, i have tried safe mode but it does the same thing, blue screen of death and back to options of startup repair and start windows normally. i don't have a restore disk, i lost but i would like to have some other option to try to fix without it.