How do you unlock dell computer screen?

The first thing I would try is to hold down the menu button for 15 seconds. This should work but if it doesn't then try this:
* Turn the computer and monitor off
* Disconnect all monitor cabling from the monitor (power, USB, VGA, DVI, etc.)
* Press and hold in the monitor power button in for 5 seconds
* Reconnect the monitor to the computer
* Reconnect the monitor power cord to the monitor
* Turn on the monitor, then the computer
* Press the Menu button for 15 seconds to unlock the padlock feature