Finder will not open in any account + bizarre behavior

Question

After setting up FileSharing in Mac OS X Server Mountain Lion, I restarted.  Now when I log into my account, or any other account I have set up, there are no files on the desktop, the desktop picture is the default, the dock is the default, there is no menubar unless I run an application, and when I click on the Finder I get the error -600 that it cannot open.
I read online that when you get the -600 error that the Finder won't open you can delete the preferences or plist files for the Finder app for that user in the Libraries folder for that user.  The thing is that I get this behavior in all accounts and I cannot navigate to the files.  I can't navigate to the files in the Finder, because there are no Finder window, menubar or icons to work with.
I am familiar with using Terminal, but for all accounts it puts me in the root directory (/) and I cannot cd into the Users folder to get at the Finder preferences/plist files.  It says I do not have permission.  When I try "sudo cd Users" and it asks for the password, it does not take the admin password (that works when I log in or change something in the System Preferences).
I also tried booting into Safe mode, but I get the same behavior.  Also, I tried resetting the PRAM, same behavior.
Any ideas what is happening or what I could do to get things back to normal?

Answer 1

Please read this whole message before doing anything.
This procedure is a diagnostic test. It’s unlikely to solve your problem. Don’t be disappointed when you find that nothing has changed after you complete it.
The purpose of the test is to determine whether the problem is caused by third-party software that loads automatically at startup or login, by a peripheral device, or by corruption of certain system caches. 
Disconnect all wired peripherals except those needed for the test, and remove all aftermarket expansion cards. Boot in safe mode and log in to the account with the problem. Note: If FileVault is enabled on some models, or if a firmware password is set, or if the boot volume is a software RAID, you can’t do this. Ask for further instructions.
Safe mode is much slower to boot and run than normal, and some things won’t work at all, including sound output and  Wi-Fi on certain iMacs. The next normal boot may also be somewhat slow.
The login screen appears even if you usually log in automatically. You must know your login password in order to log in. If you’ve forgotten the password, you will need to reset it before you begin. Test while in safe mode. Same problem? After testing, reboot as usual (i.e., not in safe mode) and verify that you still have the problem. Post the results of the test.