My machine won't boot up properly and the error message is NTLDR is missing could somone please explain how to overcome this problem

Did this just start happening? Were things working OK before?

General links here:

http://www.computerhope.com/issues/ch000465.htm

http://support.microsoft.com/?kbid=314057

http://www.google.com/search?q=NTLDR%20is%20missing

yes very recently

Thank you for your help so far

Did you find any help in the above links?