-it is a boot loader used by Windows Operating Systems.
"ntldr missing" is one of the most common error when starting a computer.
Causes:
-when your computer boots to a non-bootable device like flash drives and cd rooms.
-corrupt and misconfigured files.
How to Solve:
-Remove/disconnect all external drives from your computer then restart.
-Check the bios settings and make sure they are correct. Ensure that the first priority boot is your internal hard drive.
-Restore/repair the ntldr file from the original cd of your windows operating system.
-Check the connections inside your CPU. Make sure that your power supply can accommodate your setup. High-end computers need to have high-end power supplies also.