I cant find my user accounts

Hello,

I have a windows xp pro. I recently logged on and for some reason when I go to my log on screen it shows only one of my accounts. I had 3 user accounts on this computer and when the user selection screen should show up, it shows only my account with my name filled in ready for my password input. How can I enable the rest of the user accounts to show? I looked on the control panel and the accounts were still there, I even made a new account to test it out but whenever I should be going to the user selection screen only my user will show up. What can I do???