My computer upon opening states" NTLDR is missing press Ctrl+alt+del to restart

Have a look here as it could many causes: NTLDR is missing

On my older PC, with a floppy drive, I used to get this if I left a floppy in at shutdown with floppy first in the bios boot sequence. I also had a PC once that reset the boot sequence in the bios to a non bootable storage drive after the battery died. I had to reset it to the right drive by hitting the DEL key during boot up anding finding the boot order screen.