window xp help

i have win xp service pack 2 and there 4 account in which 4 people use the pc
so when the pc starts up it is supposed to show 4 diffreent accounts were the user can slect a username and enter the password and then go into windows.But when my pc starts it juts goes into windows.
i have tried loads of things like showing welcome screens and dat lot from the control panel but nuthin seems to work. and also before i had no password so when i want to create a password i have to type in the current password which i dont have so i leave the field blank and it says incorerect current password so wen i type somethnig in it still syas incorret password

Just something random to check - make sure autologin is disabled (this tells you how to turn it on, but it's easy enough to reverse the process):
http://support.microsoft.com/default...b;en-us;315231

If you need to reset your password, you can always use the Offline NT Password & Registry Editor. You might lose access to encrypted files and other user-related stuff, however.

My best guess from what you're describing is that someone set up a password for you, and set it to automatically log in with that username and password. It's either that or your user profile/registry somehow got corrupted.