Missing Mac HD, Dashboard & iTunes all at once - stumped the Genius Bar

I'm running OS X 10.7.3 on my mid-2010 13" MacBook Pro and randomly this afternoon, a few things stopped working.

I was browsing the web and meant to click on iTunes, but I must have dragged something on accident because the iTunes icon on my dock turned into a folder. Clicking the folder, I noticed a subfolder and the iTunes icon. I didn't think anything of it, but I dragged that folder into the trash and deleted it, thinking that I could just drag the iTunes icon back from the Applications folder into the dock. Well, that didn't work. iTunes showed up in my Applications folder, but I couldn't drag it into the dock or onto the desktop. So, I decided to restart and see if that would fix the issue.

Big mistake.

Essentially, iTunes disappeared completely from my Applications folder. Not only that, but my Macintosh HD icon disappeared from my desktop. In fact, I can't left or right click on my desktop at all! After searching around, I learned to check in Finder -> Preferences, in order to see if the box to show it was checked. It was. Not only that, but my Dashboard has disappeared completely. Pressing F4 will not bring it up, 3-finger swiping to the left won't bring it up, and it doesn't appear on the top when doing the 4-finger swipe up. Oddly, Dashboard still appears in my Applications folder, but clicking it does nothing.

I restarted several times to no avail, so I made an appointment with the nearest Apple Store. The Genius Bar checked out my MBP and couldn't figure out the problems either. For iTunes, they went ahead and just downloaded it from the Apple website. Obviously, all my purchases and library are intact, but I keep getting a notification when opening iTunes that says there's a newer version of iTunes available. I click on download and it brings up Software Update. Software Update keeps saying that all my applications are already up-to-date.

For everything else, their best suggestion was to free up some storage on my hard drive, as I only had 4 GB free out of the 250. Well, I did some of that at home (now at almost 8 GB free) and I'm still out of luck.

I've attached a few pictures to show what's going on.

Here's showing that nothing is on my desktop:
http://imageshack.us/photo/my-images/833/desktopblank.png/

My Finder Preferences showing that "Show Hard Disks" is enabled:
http://imageshack.us/photo/my-images/715/finderpreferences.png/

My Desktop folder with a test folder & screen caps, yet nothing showing up:
http://imageshack.us/photo/my-images/710/desktopfolder.png/

Dashboard missing from Mission Control:
http://imageshack.us/photo/my-images/256/dashboardmissing.png/

Yet Dashboard is still listed under Applications:
http://imageshack.us/photo/my-images/851/dashboardlisted.png/

Does anybody have any idea what's going on here?

simsaladimbamba said:

Does it also happen in another, even temporarily created, user account?

Click to expand...

I'm about to try that right now. I should add that I've already run Disk Utility -> Repair Permissions a few times now.

UPDATE: I created a test Administrator-level account and logged in with that. Macintosh HD showed up on the Desktop after checking that box in Finder -> Preferences. Dashboard was also present.

Having said that, I logged back into my main account and still nothing.

UPDATE: I just restored to a backup on Time Machine when everything was working fine (backup was from yesterday morning) and I'm still having no luck. This time, the iTunes logo is now in the dock but it's a question mark. There's still nothing on the desktop, despite those boxes being checked in Finder -> Preferences. Also, my Dashboard is still missing.

SOLVED

https://discussions.apple.com/thread/3539816?start=0&tstart=0

Basically, several plist files became corrupted. How that happens out of the ordinary is beyond me.