Hi!
My microphone is not installed in my system. Even I have attached it with my system. What you suggest me to do?

First its not a good idea to piggyback your question on someone else's. This can lead to confusion. You should start a new thread. So I've moved your question to its own thread.

You have an external microphone but its not working? Are you sure it plugged into the right jack? Are you sure its not muted? What have you done to try and use it? What version of Windows?