I use Crowbar to extract the Vpks via the "Unpack" tool.
https://steamhost.cn/steamcommunity_com/groups/CrowbarTool

I may be stupid but how do you extract a mod folder?

Rebuild the audio with the command above
or
extract the mod, and replace the necessary voice files.
There should be a *read me* in the folder. If there is no "read me", then the folders inside of the vpk are labeled with their locations.
Here's an example;
*Steam\steamapps\common\Left 4 Dead 2\left4dead2\sound\player\survivor\voice\gambler*

voice isnt working for nick

Nick, lemme add that

what character does it replace?

Mhmmm😊

ok thanks

That's correct. Once the audio fully rebuilds itself, you will be put back in and able to move around and such. The game will indeed crash, but upon reopening, it should be fine.

when i reload the audio cache by this command it should crash my game or not because after the loading of new sounds it simply turn off.

No, it does not. Rebuilding the audio cache as stated in the description will help with any ugly noises you may encounter.

Does this mod have any static sounds?