The background story:
The other day my (L)ubuntu offered me to upgrade from 12.04 LTS to 14.04 LTS, which I gladly accepted. At the end of the evening, I started the update out of the update manager, got up and went to bed, not noticing that the laptop's power was due to run out apparantly before the update had finished. After swearing loudly the next day because the PC wouldn't boot, I downloaded a Lubuntu 14.04 LTS live CD, booted from that, backed up my complete personal folder (inluding the hidden files/folders) (excluding the 39 Gigs of ~/Music I had safe on my other PC) and reinstalled Lubuntu 14.04 from scratch.
After the reinstallation, I installed quite a few programs I knew I would need/want (Skype, Mumble, PCSX, VLC and LibreOffice, just to name a few), and twiddled with a few of the system settings to create a nicer looking system. Today, I recopied the entirety of my personal folder back onto that laptop to (hopefully) restore all settings, save a few folders/files which sounded like I wouldn't need them. Logged off, tried logging back on, and my desktop is empty.
Yes, it's literally an empty desktop. No files (there should be two), standard background, no panel thingy (what I would call task bar in Windows). There's a mouse I can move. If I right-click on the background, I get a menu out of which I can open a console. (Out of the console I can open pretty much everything I've tried so far, but it's kinda … unintuitive ;)) Even though the right-click menu offers 'System -> Desktop settings', no desktop settings window will physically open.
I have a little script that should change the desktop background once every 30 mins. Attempting to start that script results in an error message saying the desktop is not active.
Which prompts my questions:
Which (required) file(s) and/or folder(s) have I most likely overwritten (and probably rendered unuseable?) when porting the complete user folder onto the newer version?
How can I get a working desktop back?
Are there any other hidden traps I might stuble into in the near future?
Thanks for your help and apologies if there are answers around here somewhere that I was too stupid to find!