How to detect a keylogger (as a hidden program) if the antivirus could not detect it in windows operating system?

Mr.Abdullah Al- Hamed,

  However, as for a software keylogger, it can be run while being completely invisible and not get noticed by average computer users. They’ll have to fully depend on security software such as anti-keyloggers or antivirus packages to tell them that a keylogger is present on the system,or else they have no ideathat everything that they do on the computer is being monitored....

Dear,

 first off all :

1- you need to download a several softwares like:

a- Spyboot search & destroy : http://www.safer-networking.org.

b- Malwarebytes from: http://www.malwarebytes.org

c- HijackThis from : http://sourceforge.net/projects/hjt

d- don't forget to download the offline updates for each software if available.

2- try to keep a copy of these software in your computer before you restart.

3- login to your windows as administrator in safe mode (without networking), by pressing F8 after you restart your machine.

4- use these software from top to down (after updating).

The next logic step is to clean & delete any detected keylogger.

Best regards