I went to this server and it changed my sounds around somehow like my lmg sounds like a pistol and my hmg sounds like GL please help.

Eh? Didn't know that was possible. Maybe you will have to delete and reinstall NS (just NS) and it will be fine.

I'm also having this problem. It started when I went to the Battle For the Galaxy server. Now it stays that way whenever I go elsewhere.

Skulk bite has the sound of the lerk bite, I constantly hear these knife whiff sounds, using bilebomb gives me what appears to be the acid rocket attack, etc.

Lol talk about lame servers... Just reinstall NS or manually undo the changes (may be hard)

No need to go that far! I had the same problem, quite amusing for some time (pistol fired like a shotgun!!) thought it was some sort of new excessive plug in, lol! Just restart steam, should be fine!