BSOD error... Unamountable boot volume

Have you tried spamming delete key before it boots to load up bios and check the boot drives? Before you do that, restart your PC, and see if windows will repair its own corrupted files. and if that doesn't work you'll need to reinstall windows. You can create a windows installation media by using this link and putting it on a flashdrive. just plug it into your pc, load bios and change boot order to the new windows installation media. Its pretty simple from there, and there are mountains of videos online for how to do it.