If I login on my Ubuntu 14.04, I get the following desktop:

This weird behavior appeared after I executed sudo apt-get update && sudo apt-get upgrade and restarted my computer. Don't know why though.

To my Ubuntu I have tried the following (nothing seems to work so far)

Fix any broken packages:

sudo apt-get update
sudo apt-get autoclean
sudo apt-get clean
sudo apt-get autoremove

Locate any broken packages and reinstall them:

sudo apt-get install debsums
sudo apt-get clean
sudo debsums_init
sudo debsums -cs
sudo apt-get install --reinstall $(sudo dpkg -S $(sudo debsums -c) | cut -d : -f 1 | sort -u)

Removing some compiz files:

rm -r ~/.cache/compizconfig-1
rm -r ~/.compiz

Purging of NVIDIA and installing NVIDIA-prime:

sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get install unity
sudo apt-get purge nvidia* bumblebee*
sudo apt-get install nvidia-prime
sudo shutdown -r now

Compizconfig Settings Manager:

sudo apt-get install compizconfig-settings-manager

export DISPLAY=:0
ccsm

// Back to UI and enablement of Unity Plugin

Unity replace, which stopped at a while and did nothing afterwards

unity --replace

Some dconf reset

dconf reset -f /org/compiz/
unity --reset-icons &disown

Actually dconf did not work and I got this error:

error: Cannot autolaunch D-Bus without X11 $DISPLAY

Can anybody help me on that?

This is my hardware (hope it helps in any way):

• Intel® Core™ i7-3770
• ASUS GTX660TI-DC2-OG-2GD5 (NVIDIA driver is/was installed)
• ASUS P8Z77-V LX
• Corsair DIMM 8 GB DDR3-1600 Kit
• Samsung 830series 2,5" 256 GB (Windows is installed here)
• Seagate ST31000524AS 1 TB (3/4 are reserved for files; 1/4 is for Ubuntu (16GB swap included))