Short version: I need to format my HDD to NTFS with no current OS. Long version: I was happily running Windows 10, but wanted to do a re-installation to speed things up. The installation hung at 1% for an hour or so, so I rebooted - no operating system. I downloaded a win10 iso and booted from there. All good, but windows is not verified. Windows won't accept the win8 Pro key which I was originally using, so; I installed Ubuntu (I only use this as an HTPC for Kodi. I decided I didn't like Ubuntu, so downloaded a win 8 pro iso. When trying to install, I get the error message that the disc is not a recognised format. The format drive icon is grayed out. How do I get my system back up and running? I guess I need to format the drive. Also, I cannot create a CD ROM, so needs to be able to boot from USB.