You don't say if your PC is a desktop or a laptop. If it's a desktop, slave the drive that won't boot to a bootable drive with Windows 8 Pro on it and follow the directions below. If it's a laptop, connect and boot from a bootable Windows 8 hard drive in an external enclosure. Once Windows is up and running, see if you can access the drive installed in your PC. There could be many reasons why your PC won't boot. It may not be because the drive is bad. If you can access the installed drive, copy your files to the external drive. Once that's done you've saved your files. Now you need to find out why your PC isn't booting. I would start by running diagnostics on your PC to see if that reveals why your system is not booting. Could be the MB is bad. Could be the memory. Could be the CPU. Could be a lot of things, not just the hard drive. Good luck and next time ALWAYS backup your files.