StorageFolder Folder1 = await StorageFolder.GetFolderFromPathAsync("C:\\SomeFolder");
Accessing System Folders
Not all folders are accesible by Universal Windows Apps. To make a folder accesible to a UWP app, you can use FolderPermissions command line tool.
E.g., give UWP apps access to c:\test folder:
FolderPermissions c:\test -e
Note this will work only with native Win32 apis for eg. CreateFile2 and not with WinRT apis like StorageFolder, StorageFile etc.