Here list 3 methods on how to reset Windows password on Vista.

Method 1: Reset Vista password with typing “ Ctrl + Alt +Del"
Step 1: Start your computer. On the login screen, enter "Administrator" or another username in the username field, and the appropriate password in the password field. Press "Enter."
Step 2: Press "Control," "Alt" and "Delete" simultaneously.
Step 3: Click "Change a Password" and select your username. Enter a new password twice for confirmation, then click "Okay." Log off your computer, then reboot and login with your regular username and new password.
Method 2: Reset Windows Vista password with Control Panel
Step 1: Click "Start" on the computer taskbar.
Step 2: Select "Control Panel" and then click "User Accounts and Family Safety."
Step 3: Click "User Accounts." Click the "Change Your Password" link.
Step 4: Locate the user account that requires the password reset.
Step 5: Right-click the user account icon, and then click "Set Password" from the context menu.
Step 6: Enter the new password into the first input field, and then enter the new password again into the second input field. Click the "Change Password" button. This resets the password for the user account.
Well, the above 2 methods are available provided that there is anothor more user account with administrator right to reset Vista password.
Method 3: Reset Vista password with a professional password recovery tool
If you have downloaded a Windows password recovery tool, it is easy and safe to reset the forgotten password on Windows Vista. Now, take Windows Password Unlocker for example, it is an efficient and professional tool designed to remove Windows Vista password with a password reset disk boot from a bootable CD/DVD/USB flash drive.