Did you know that if you have two different "User Accounts" on a computer, you can only "Sign On" to just one at a time. So the computer stores information completely different from the other account? Yes. This is for privacy between different people.
I did this by accident, I have two accounts and I was working on one, and when I came back a week later I signed on to "wrong user account" so my work was not there after signing on.
Later after thinking about maybe using "Time Machine" to restore my files, I remembered having the two "user accounts". So I restarted the computer and signed on as the other "user account" and found all my updated information.
File Sharing Between User Accounts
You can use "share folder" that allows transfer data between two accounts.
http://support.apple.com/kb/HT3309
