Hello, I would like to ask a question about the weapon sounds. I want to make mod for CS2D. I decided to replace the sounds with USP and M4A1, but they do not play in the game. And other weapons, yes. Tell me, what is the problem and how to solve it? Same thing in CS 1.6, CS:CZ

Maybe you didnt replace with right format, or with right name... regardless of that, idk how you did it but it would be best to replace it, not delete then copy if you know what i mean

In case you're using wav: There are many of different wav encodings and not all of them are supported. Try saving your file with another encoding.

If you want to make sure that it works you can also try ogg instead. ogg files always worked for me so far with CS2D.

On this site you can transform your sound files to ogg
the archives adopt a very light weight thanks to the fact that the site apart from transforming them also compresses them.
https://audio.online-convert.com/es/convertir-a-ogg

No-no-no-no-no-no-no-no

https://www.audacityteam.org/download/ is a free audio editor, load your track and go to File → Export As... → Choose ogg/vorbis.
The file will be MUCH smaller and have much higher quality than .wav