@osamaahmed2000, your topic has been moved to a more suitable location on the forum. Installation and Troubleshooting is not for problems with (nor for advise on) your project 
See About the Installation & Troubleshooting category.
What is a key in this? A button?
This sounds like a job for the state change detection example that comes with the IDE; do not detect when a button is pressed but detect when it becomes pressed.