Desktop is being blocked - neverending story

[mecho]

In terminal
ls -ld /home/knoppix/Desktop

You should see something like this:
drwxr-xr-x 2 knoppix knoppix 4096 May 25 07:09 /home/knoppix/Desktop

DRWXR means - D - directory R-read W-write X-execute for owner
XR is read and execute for the group and for other users. If you see this it means your permissions are fine

[GizmoPlushie]

Let's assume settings are fine and I mistakenly - as a newbie - changed them to another more limited group:

So,

1). Is it possible to change it back?
2). Will it restore desktop icons / root folders - functionality? (like drag and drop icons, see them like miniatures and the most important: right click on the dekstop?)