1- Right click on your computer screen and click on “New” and then on shortcuts.
2- After clicking on shortcuts and then copy and paste the following code in the text box
rundll32.exe user32.dll, LockWorkStation
3- Now click on the Next and it will ask you to name your shortcut.
4-Put in your desired shortcut name.
5-Now Click on the finish button
6-And that it.Your Shortcut button to lock your computer screen is ready.
There is also a secand method to lock your computer screen using keyboard
shortcut and the keyboard shortcut is WINDOW KEY+L and that it.