Need help with computer ntldr is missing press ctrl+alt+del to restart? I tried to restore it.................?

with all the restore points and none of them worked. I used to have windows xp and installed windows 7 the day before it happened. Before this happened I was updating my computer and it said something like windows is configuring your system and it failed so I restarted it. I really need help please help my computer is A (DELL LATITUDE D620)