How do I fix NTFS from Ubuntu?

You can try to use ntfsfix in order to repair the NTFS volume. This is a 'solution' in that it can fix simple errors such as the MFT and MFTMirror not matching up, and some minor filesystem incongruities. Note that if nftsfix doesn't fix the drive up so it's usable, you'll need to use the tried-and-true "Use a Windows system to repair NTFS" solution.

sudo ntfsfix /dev/sdXY (where X and Y are the letter of the drive's device and Y is the partition number, you can get this data off of sudo fdisk -l but it looks to me like this should be /dev/sdc1 for your specific case) should then work.

Note that the still tried-and-true "complete" solution for fixing NTFS problems is a Windows system or a Windows boot disk (or even a Windows VM that you pass the external USB drive through to), and using chkdisk from the Windows system.