Apparently, some folders are hidden. A case in point is the System Information folder that by default can be up to 50%, if you don't decrease that percentage yourself (it's used for system restore info and shadow copies).
Download Treesize Free from http://www.jam-software.com/treesize_free/ , run it and see what you don't see now.
Hey guys i don't know what to do anymore i tried everything, and i still don't know what happened to my approximately 35 GB . Please Help!
Here are some screenshots.