Multiplayer not working after installing client

Whenever I run the game this image comes and it crashes automatically single player is working good but this is not please help.

You have not really given us much to go off.
Are you on disc version or steam or cracked copy?
How have you installed the CoD4x client?

It is a cracked version which I downloaded from steamrip I installed thr Cod4x client 21_1 I pasted the folder in the game file and pressed the install cmd file files were were copied sucecessfully and then I launched the game it shows that picture and automatically closes.

That’s probably your issue, it being a cracked version.

I don’t know what Operating System You Use But I’ve Had the same Problem on Windows 8. The Multiplayer just shows the image and closes back. When I upgraded to Windows 10, The Problem Stopped

It was working previously I was even able to join servers but the game used to crash in between but after downloading client it ain’t opening

I am already at windows 10

Turn on the stereomixer or turn off the steam