I would back my files up to the cloud and re-populate that space to your C: drive provided you are talking about that drive, or whatever drive you used. You can do that by going to disk management from the control panel or you can use command prompt, I recommend using the GUI. If that doesn't work you can always reset or re-format the drive and reinstall Windows 10. Before you do that make sure you sync and backup your files and settings first(always #1). I hope that helps as I'm a bit old school. :)
