Another edit: Can you run the 'ln' command? try it with this:
If you can run this command then try this:
This should link the new position to the old one and hopefully get things working again.
sudo ln -s /usr/lib/lib /lib
Out of curiosity how is rebooting going to solve this problem? He's moved his /lib folder, rebooting won't move it back. Your best bet is to boot from a LiveCD (The installer disc is good if you still have it about) and to move the folder back to where it was.
Can you boot up a LiveCD, goto a terminal (Applications > Accessories > Terminal) and run this command:
And post the output here? This will let us figure out which drive you need to access from the LiveCD and hopefully help you sort this all out.
Try this AFTER you post the output of the last command and I get back to you.
Make sure you replace <hd> in the commands with the name of the hard drive we find from the earlier command.
You should be able to fix it reasonably easily if you boot the LiveCD up, open a terminal (Applications > Accessories > Terminal) and run these commands:
sudo mkdir /media/ubuntu
sudo mount /dev/<hd> /media/ubuntu
This should move your /lib folder back to the correct place. After this you should be able to restart the computer and Ubuntu should be working again.
sudo mv /media/ubuntu/usr/lib/lib /media/ubuntu/
Edit: You moved the libaries for most programs from the place they are expected to be. Which unfortunately is the rough equivilent of taking a cars engine and putting it on the roof. It's still an engine but it's not going to be looked for there and it isn't in the right place to do anything useful.