I am reporting this bug two days after it occurred and I was able to fix it, so some things might be vague. I believe this issue is connected with my accidental install of virtualbox virtualbox-4.3_4.3.12-93733~Ubuntu~raring_i386 instead of the appropriate virtualbox-4.3_4.3.12-93733~Ubuntu~raring_amd64 for my system. I after I uninstalled the i386 version, when I went I clicked on the .deb package in my download folder, ubuntu software center seemed to open but there were several odd occurrences. Instead of the usual icon on the sidebar (an orange grocery bag with a white A), I got a ? mark icon. I was also unable to install virtuabox amd64. When I went to open the terminal with the keyboard shortcut ctrl+alt+T, instead of receiving the usual gnome terminal, XTerm opened instead. When I tried searching for terminal in the unity search, Xterm and UXterm were the only options. For an unrelated reason I needed terminal, I then tried to open the Transmission bittorrent client but I noticed it was missing as well. That was when I tried to open Ubuntu Software Center directly and was unable to find it. After that, I decided to reboot the system. I did so via the power button on the bar in the top right corner.
When the computer restarted, I was greeted with my usual password prompt. However when I logged in the only thing I was greeted with was my desktop and the files I had on it. There was no sidebar or bar at the top. None of the typical shortcuts worked (ctr+alt+T, Ctrl+Alt+Backspace), but the the ctrl+alt+delete shortcut I had set to open the system monitor did. I restarted a few times with the physical reset button on my tower. After some research, I logged in after a restarted and used the ctrl+alt+F1 to go access terminal. I installed the unity-tweak-tool and ran unity-tweak-tool --reset-unity and the sudo reboot. After I logged back in, Unity had returned. I had to reinstall Ubuntu Software Center from Xterm and reinstall gnome terminal and transmission. Everything seems back to normal now however the system monitor appearance is different. The border around it is different and there's no background when I go to the resources tab, making it hard to read.
ProblemType: Bug
DistroRelease: Ubuntu 14.04
Package: unity 7.2.1+14.04.20140513-0ubuntu2
ProcVersionSignature: Ubuntu 3.13.0-29.53-generic 3.13.11.2
Uname: Linux 3.13.0-29-generic x86_64
ApportVersion: 2.14.1-0ubuntu3.2
Architecture: amd64
CompizPlugins: [core,composite,opengl,compiztoolbox,decor,vpswitch,snap,mousepoll,resize,place,move,wall,grid,regex,imgpng,session,gnomecompat,animation,fade,workarounds,scale,expo,ezoom]
CurrentDesktop: Unity
Date: Sun Jun 15 17:01:34 2014
InstallationDate: Installed on 2014-06-02 (13 days ago)
InstallationMedia: Ubuntu 14.04 LTS "Trusty Tahr" - Release amd64 (20140417)
ProcEnviron:
LANGUAGE=en_US
PATH=(custom, no user)
XDG_RUNTIME_DIR=<set>
LANG=en_US.UTF-8
SHELL=/bin/bash
SourcePackage: unity
UpgradeStatus: No upgrade log present (probably fresh install)
