When you ran WirDirStat (post #6), did you start it with "Run as administrator"?
If not, can you start it with "Run as administrator", and see if the space used is different?
For me, "Run as administrator" makes a difference in how much is displayed for space used...
I'm wondering if this might not explain the difference in WirDirStat vs. Windows Disk Management.
Forgot to mention this may be the ssd drive. I'm not sure what else it could be. But i have a ~64gb ssd that comes with lenovo y570.
It sounds like you also have an SSD as Disk 1 that is now "Unknown/Not Initialized" and came with the Laptop.
Did the laptop come with the OS installed on this SSD, and you "re-installed" the OS on the HD?
If so, how did you "re-install" to the HD?
Why do you have an SSD that came with the Laptop and is Unknown (not used)?