Verified answer

forgive for asking this but if it is locked how are you able to use it to post this question ?

One method of gaining access to the system is by trying hard to remember the forgotten password, or a password of another user which has the same level of administrative rights. However I don't think this approach will help you, otherwise you wouldn't be sitting here reading article, would you? Another method is by trying to restore a backed up System State (in Windows 2000/XP/2003) or a ERD (in NT 4.0) in which you do remember the password. The problem with doing so is that you'll probably lose all of the recently add users and groups, and all the changed passwords for all of your users since the last backup was made. A third method might be to install a parallel operating system on a different partition on the same computer, then use a simple trick to gain access to the old system. A fourth method would be to turn off the computer turn it on as safe mode and reset your password.

You may have the screensaver option to lock the computer set after a certain timeframe. You type in your password to unlock it. To adjust the settings afterwards right click on an empty area of your desktop, select Properties, select the Screen Saver tab and you should see an area to adjust the time settings and a box to add or remove a tickmark titled "on resume, password protect". If you make any adjustments, click Apply then click OK. You may need to reboot for the change of settings to fully take effect.

Press Control+Alt+Delete, a prompt will appear, enter your password to unlock - if you don't have a password, just press 'enter' and it *should* unlock.

It could have been triggered by a screensaver, or you could have accidentally pressed windows+L.

ctrl+alt+del