So, I downloaded a thing called AOMEI for more space on my drive, then the laptop said that it ran into a problem. So, I restarted it, but now it keeps saying "No bootable devices."
If it helps I have a Dell Inspiron 14 3000 series with Windows 10
had the very same issue.. either dead HDD or sata cable detached... open the HDD cage and re inser every cable... if not the case check the bios when posting and see if it detects hdd.. if yes change boot priority to 1st HDD