jake43 0 Newbie Poster

When I turn on my computer, it would say NLDR missing Press ALT CTRL DEL to restart the computer. Does anyone have an idea?
I tried recovery tools but when it gets to 77%, it would say that the file is corrupted. I also tried to format the hard drive using usb stick, but the computer won't recognize it even though it says on the bios to boot up from this drive. I ran out of ideas, please help.
The computer is Acer ZG5 this model does not have cd/dvd drive built in.