Ntldr missing; blank blue screen while trying to reinstall xp

[PrasB]

There was this virus ntdetect.exe which came into my computer.Later when I tried to restart I was unable to do so and it gave a message saying 'ntldr missing'.So I tried to reinstall the xp once again but while doing so it went uptill 'Press any key to boot from cd' .When I do that it shows a blank blue screen. Which is the easiest way to get around this problem?How do I reinstall xp if that is the easiest thing to do?Please help..