Hard disc space

Can anyone please help me with a problem that's driving me nuts.
I am running Windows 7 on a 1 TB hard drive.
The total size of files/programmes on the hard drive is 497GB. But, I only have 41.9 GB free???
I have run WinDirStat, & it shows an "unknown" space of 434 GB. This section is a yellow colour, & does not show any files. I cannot alter it or delete it, so how can I recover this 434 GB.
I have run cc cleaner, disk defrag etc. but no joy.
I haven't got windows restore active as I use a programme called Rollback RX ,which allows me to revert back to an earlier save point.
I have run WinDirSat & also Treesize. I have attached the results.

https://imgur.com/a/SLEZ4

https://imgur.com/a/2Ew0r

Can anyone please help me?
Regards
Dave

Thank you for helping me. I have attached a screenshot below.
Dave


https://imgur.com/a/tsEHm

Paul,
I hadn't noticed that, well spotted. Anyway, I can't answer your question. My hard drive was replaced by a new one about 4/5months ago, & Windows 7 was reinstalled on it. The current time/date on my computer is correct.
Dave

Please don't use external links to images. Use the paper clip (on quick reply window) - browse to the file - upload.
I can see almost an identical drive on disk 1.
Did you created an disk image and stored on drive C:?

Oilman5678 said:

I have run WinDirStat, & it shows an "unknown" space of 434 GB.

WizTree can often show the files that WinDirStat lists as unknown.

Antibody Software - WizTree finds the files and folders using the most disk space on your hard drive

I have attached the Wintree file showing that approx.half of my hard drive capacity is missing(?)
I have also attached other results from WinDirStat etc.
Please, can anyone advise?
Dave

Run a check disk on drive C: (chkdsk c: /f). You may have cross links.