Fix Broken Folder

I'll share this experience here in case it can help anyone. This morning I was copying a bunch of films on Ubuntu from my laptop to and external NTFS disk. The copying got stuck at 50% and after a while I cancelled it. The usb disk seemed to be still in use but anyway I disconnected it (as so many times before). When connecting it again it looked fine, save for the folder "Films" on which I was copying the files. Opening the folder from the UI it showed up empty. From the command line I could do a cd into it, but doing a ls would return reading directory '.': Input/output error

I did not enter into panic as all the other folders with important stuff (and already backed up in other disks) like personal pictures, documents... seemed intact, so I was only losing like 400 films... (many of them scattered over other old, smaller, external disks). Anyway, managing to recover the folder would be nice...

The first thing I found about was running the badblocks command to verify that the disk was physically OK (I honestly thought so, as all the other folders looked good I was more leaning to think of a file system error). badblocks was taking so long, so I did a fast search and found that it could take up to 70 hours!!! and just to verify something, not to fix the disk...

I read by passing something that I already knew but was missing, that even if NTFS disks are perfectly supported in Linux since a very long while... it's Microsoft who has the full knowledge of the system, so I thought I could check if Windows was able to recognize the folder.

Rebooting my laptop on Windows and trying to navigate the folder I got this error:
The File or Directory is Corrupted and Unreadable

A fast search brought up this article, that recommended doing a chkdsk /f on the problematic disk.

After a few seconds the first messages stating that some error had been found and had been fixed showed up, so it was quite reassuring. After less than 10 minutes (for a 2TBs disk with a 30% use disk), the procedure was finished and the contents of my "Films" folder were back again! I'm putting below some of the fix messages that chkdsk returned: