Unity will not boot/load after upgrade from 13.10 to 14.04

There are many similar post on ask ubuntu and I have gone through them with little success.

I upgraded from 13.04 to 13.10 to 14.04 back to back. The upgrade from 13.03 to 13.10 worked fine. After the upgrade from 13.10 to 14.04 I ran into a problem. After logging into my computer I am left with only the background image and no other desktop or unity elements. No key bindings work ( ctrl+alt+t for example). I am able to drop into a terminal using ctrl+alt+(f1+f6). Once logged into a terminal I am able to run things like apt-get and other shell utilities. I can not run anything graphical without first telling the terminal where to send it by exporting display 0 export DISPLAY=:0 Once I have done that I can run gui based programs like Firefox.

One thing to note, if I run nautilus from the terminal it shows me the desktop and the bar at the top of the screen with the nautilus options ( File Edit View Go Bookmarks Help ). I have tried re-enabling unity from CCSM, no change, I have reinstalled unity and Ubuntu-Desktop, no change. I have uninstalled and reinstalled nvida-current drivers , again, no change.

I have done everything I can think of to investigate this problem ( which is not much since I am still pretty new to this). If there is anything I should do to further investigate this let me know and I will run it asap. I am still able to switch the standard output to a file on the desktop and access it from there. Any help would be greatly appreciated

• edits to grammar and spelling were applied.

Update:

Based on the suggestions made in this post. I did the following;

 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

Now, after I log into my computer I see the items on my desktop. I can also open nautilus by pressing ctrl+n. The ability to right click has returned which allows me to open a terminal. However, ctrl+alt+t still does not work. I am unable to grab and move any windows around or bring program windows from the back of the desktop to the front by clicking on them. They stay stacked in the order I opened them, with the most recent window on top. I checked Compiz Setting Manager again and unity is activated.

Update 2:

I think this may be an opengl problem. I ran the following command in the Termial;

DISPLAY=:0 unity

and I get the following output before the terminal hangs.

 compiz (core) - Info: Loading plugin: core
 compiz (core) - Info: Starting plugin: core
 unity-panel-service start/running, process 2707
 compiz (core) - Info: Loading plugin: ccp
 compiz (core) - Info: Starting plugin: ccp
 compizconfig - Info: Backend     : gsettings
 compizconfig - Info: Integration : true
 compizconfig - Info: Profile     : unity
 compiz (core) - Info: Loading plugin: composite
 compiz (core) - Info: Starting plugin: composite
 compiz (core) - Info: Loading plugin: move
 compiz (core) - Info: Starting plugin: move
 compiz (core) - Info: Loading plugin: place
 compiz (core) - Info: Starting plugin: place
 compiz (core) - Info: Loading plugin: snap
 compiz (core) - Info: Starting plugin: snap
 compiz (core) - Info: Loading plugin: commands
 compiz (core) - Info: Starting plugin: commands
 compiz (core) - Info: Loading plugin: compiztoolbox
 compiz (core) - Info: Starting plugin: compiztoolbox
 compiz (core) - Error: Plugin 'opengl' not loaded
compiz (core) - Info: Loading plugin: resize
 compiz (core) - Info: Starting plugin: resize
 compiz (core) - Info: Loading plugin: regex
 compiz (core) - Info: Starting plugin: regex
 compiz (core) - Info: Loading plugin: mousepoll
 compiz (core) - Info: Starting plugin: mousepoll
 compiz (core) - Info: Loading plugin: imgpng
 compiz (core) - Info: Starting plugin: imgpng
 compiz (core) - Info: Loading plugin: vpswitch
 compiz (core) - Info: Starting plugin: vpswitch
 compiz (core) - Info: Loading plugin: session
 compiz (core) - Info: Starting plugin: session
 compiz (core) - Info: Loading plugin: workarounds
 compiz (core) - Info: Starting plugin: workarounds
 compiz (core) - Error: Plugin 'opengl' not loaded

I am not sure what to do about this, opengl does not seem to be missing in general since i am able to run graphically intensive programs. However, I am not sure if the opengl plugin is a different thing then opengl used for things like gaming ( I feel shame admitting that ). I am off to do research on this and will report back when I have some more information.

OP here, I finally had success!

I am combining all of the steps I ended up doing before I had success

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

After the restart log back in and drop to a terminal in any way you can. At this point I was able to open a terminal by right clicking a blank place on the desktop and selecting open in terminal. Them enter the following set of commands

DISPLAY=:0 unity
dconf reset -f /org/compiz/
unity

and unity finally started right up and everything is working fine now.

if the command unity does not start it back up at the end try setsid unity

I hope my trials are helpful for someone out there. Thanks to anyone who gave this thread a look and everyone who commented.