Windows 10: Invisible folders/files occupying space on C Drive

On my Desktop Win 8.1, the Properties dialog for all folder shows they occupy 133 GB space. The chkdsk command shows that 143 GB space is occupied. I can't find out who has occupied this 10 GB space. I need to recover this to make space on my hard drive.What can I do to get this space free.

:)

 

Discrepancy between 'Used Space' on C drive and total of actual folders/files

According to 'Properties' in Windows Explorer, my C drive (one of four partitions on my primary drive) has 296GB 'Used Space' and 272GB 'Free Space', giving a total partition size of 568GB. However, if I add up the total space occupied by all the folders
and files on C drive that are listed in Windows Explorer they come to roughly 44GB. (The largest folder is Windows (19.5GB), followed by Users (9GB) and Program Files (5.8GB). The rest of the folders are smaller than this.). Nearly all my applications, data,
photos, videos, backups etc are on the other three partitions on the primary hard drive or on a secondary internal hard drive.

Can anyone suggest what accounts for the HUGE discrepancy between the reported 'Used Space' and the total of the actual folders/files? I first noticed this when backing up my C drive using Acronis TrueImage, which yields a back up file of 218GB - presumably
the 296GB with some compression. A few months back I recall that the Acronis backup files were sized at around 60-70GB, so there's something funny going on! If there is some giant folder or file that is lurking on my C drive, what could it be and why isn't
it showing up in Windows Explorer?

 

Unallocated Space to C Drive

Thanks

 

C drive space filling

My C drive space in Windows 10 is filling up rapidly. I tried deleting CBS files but that weren't occupying much space.

I used Treesize but not able to make sense of which file is occupying unnecessary space and which file to delete.