The NTLDR and Ntdetect.com files are important system files that are used by your computer to start the Windows XP operating system. These files can become damaged, corrupted or deleted for a number of reasons and are usually brought to your attention by the "NTLDR is Missing" error message.
Follow these easy steps to restore the damaged/corrupted or missing NTLDR and Ntdetect.com files from the Windows XP CD using the Recovery Console.
Time Required: Restoring the NTLDR and Ntdetect.com files from the Windows XP CD usually takes less than 15 minutes
When you reach the command prompt (detailed in Step 6 in the link above), type the following two commands, pressing Enter after each one:
copy d:\i386\ntldr c:\
copy d:\i386\ntdetect.com c:\
In the command listed above, d represents the drive letter assigned to the optical drive that your Windows XP CD is currently in. While this is most often d, your system could assign a different letter. Also, c:\ represents the root folder of the partition that Windows XP is currently installed on. Again, this is most often the case but your system could be different.
If you're prompted to overwrite either of the two files, press Y.
Take out the Windows XP CD, type exit and then press Enter to restart your PC.
Assuming that missing or corrupt versions of the NTLDR and/or Ntdetect.com files were your only issues, Windows XP should now start normally.