‘NTLDR or Is Missing’; ‘Press any key to restart’

Hi experts
I have tried to start My laptop but it won't open today. However it was running very well when I turned it off last night.
At the time of startup, I find the Dell loading display briefly, and then I just see a black screen and find some error messages.
It shows 'NTLDR or Is Missing' as well as 'press key to restart, which makes it to do again the same things.
Then I tried to boot from my Windows Vista Disc to solve it but Startup fix won't work.
Please help. Thanks a lot.
