Microsoft has removed the classic Windows NT style logon screen in Windows Vista. You can no longer hit CTRL+ALT+Delete to get to a logon box where you can type in the username and password. Instead you have to enable the alternative logon screen to restore this capability.
- Click on the Start Button, key in secpol.msc and hit Enter.
- Navigate through Local Policies and Security Options.
- Locate and right click on "Interactive logon: Do not display last user name" and select Properties.
- Select Enable and hit OK.
- close Local Security Policy editor.
Log off and you will see the new logon screen.
Tip: If you need to log into a domain sign in with "domain\username". If you want to log into a local computer account, sign in with ".\local_username".
Keep in mind that depending on how you configured your local accounts your actual username may be different than the display name. For example in my Active Directory implementation my account shows up as Steve Sinchak by my actual login name is steve.
Worst case scenario you could use one of the Linux admin password reset boot CD's to reset the local admin password on your computer. Search google, there are a lot of free options.