My laptop suddenly crashed and when I turned it on it said that no boot devices found. How do I fix this thing (my harddrive is externally ok. It displayed my harddrive in bios)
There is a possible chance that your laptop's O.S. has been corrupted very badly that it can't be found. If you have another laptop and a USB, install Windows O.S. installer onto the USB then plug the USB into the dead laptop.