When I turn it says ntldr is missing what can I do to fix it

NTLDR (New Technology Loader) missing is saying the machine can't find the Master Boot Record and therefore can't boot. It could be a defective hard drive or a virus. You need to locate a utility that will boot from an emergency startup disk and repair or replace the Master Boot Record or else, reformat the drive and reinstall the operating system. The utility depends on which version of Windows you're running.