Re-start that computer and when you do, poke (not hold) the F8 key every second until a screen appears with many choices of how to start your computer.
Use the cursor keys and select "Start in Safe Mode" the press the enter key.
If you get a screen asking what system you want to start, choose your Windows XP.
Eventually, you will have a choice of what account you wish to log in with, choose "Administrator"
You will also be asked later if you want to perform a System Restore Point Rollback.
Choose answer to continue to run Windows in safe mode.
When the desktop finally appears, Click Start>Control Panel>User Accounts
Once there, click on your own account and then click Change Password.
Enter a new password and click Ok, restart computer and use your new pass to log in.
Edit: /hears song playing in background... Bob Dylan 'The Times They are A-Changin'